WO2004053498A1 - ペプチドのc末端アミノ酸配列解析方法 - Google Patents
ペプチドのc末端アミノ酸配列解析方法 Download PDFInfo
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- WO2004053498A1 WO2004053498A1 PCT/JP2003/015522 JP0315522W WO2004053498A1 WO 2004053498 A1 WO2004053498 A1 WO 2004053498A1 JP 0315522 W JP0315522 W JP 0315522W WO 2004053498 A1 WO2004053498 A1 WO 2004053498A1
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- G—PHYSICS
- G01—MEASURING; TESTING
- G01N—INVESTIGATING OR ANALYSING MATERIALS BY DETERMINING THEIR CHEMICAL OR PHYSICAL PROPERTIES
- G01N33/00—Investigating or analysing materials by specific methods not covered by groups G01N1/00 - G01N31/00
- G01N33/48—Biological material, e.g. blood, urine; Haemocytometers
- G01N33/50—Chemical analysis of biological material, e.g. blood, urine; Testing involving biospecific ligand binding methods; Immunological testing
- G01N33/68—Chemical analysis of biological material, e.g. blood, urine; Testing involving biospecific ligand binding methods; Immunological testing involving proteins, peptides or amino acids
- G01N33/6803—General methods of protein analysis not limited to specific proteins or families of proteins
- G01N33/6818—Sequencing of polypeptides
- G01N33/6821—Sequencing of polypeptides involving C-terminal degradation
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- G—PHYSICS
- G01—MEASURING; TESTING
- G01N—INVESTIGATING OR ANALYSING MATERIALS BY DETERMINING THEIR CHEMICAL OR PHYSICAL PROPERTIES
- G01N33/00—Investigating or analysing materials by specific methods not covered by groups G01N1/00 - G01N31/00
- G01N33/48—Biological material, e.g. blood, urine; Haemocytometers
- G01N33/50—Chemical analysis of biological material, e.g. blood, urine; Testing involving biospecific ligand binding methods; Immunological testing
- G01N33/68—Chemical analysis of biological material, e.g. blood, urine; Testing involving biospecific ligand binding methods; Immunological testing involving proteins, peptides or amino acids
- G01N33/6803—General methods of protein analysis not limited to specific proteins or families of proteins
- G01N33/6842—Proteomic analysis of subsets of protein mixtures with reduced complexity, e.g. membrane proteins, phosphoproteins, organelle proteins
Definitions
- the present invention relates to a method for analyzing the C-terminal amino acid sequence of a peptide, and more specifically, to a peptide, for example, a peptide having a large number of amino acid residues, such as a protein, by sequentially analyzing the C-terminal amino acid of the peptide by a chemical method.
- the present invention relates to a method for elucidating the C-terminal amino acid sequence based on the molecular weight reduction of a series of amino acids that are sequentially decomposed, and the molecular weight of the reaction product is determined by mass spectrometry.
- Identification of amino acid sequences of peptides and proteins collected from nature is essential information when studying the biological properties and functions of such peptides and proteins.
- the entire amino acid sequence of peptides and proteins is based on the corresponding genetic information, that is, the amino acid deduced based on the genomic gene encoding these peptides and the nucleotide sequence of c-DNA prepared from m_RNA. It has been determined as an array.
- knowledge of the partial amino acid sequence of the peptide is still necessary in order to identify the genomic gene encoding the peptide and the c-DNA prepared from the mRNA.
- the N-terminal amino acid sequence and the C-terminal amino acid sequence of the peptide are particularly useful.
- the target c-DNA can be selected using the prepared nucleic acid probes based on the amino acid sequences at both ends.
- the PCR method is applied using oligonucleotide primers prepared based on the amino acid sequences at both ends.
- the target c_DNA can be selectively amplified.
- a high-concentration aqueous solution of pentafluoropropanoic acid (CF 3 CF 2 COOH) is added to dried peptides while heating to 90 ° C, or Heptafluorobutanoic acid (CF 3 CF 2 CF 2 COOH)
- CF 3 CF 2 COOH pentafluoropropanoic acid
- Heptafluorobutanoic acid (CF 3 CF 2 CF 2 COOH)
- the selective decomposition reaction of the above c-terminal amino acid proceeds sequentially, and after a predetermined processing time, 1 to 10 amino acid residues are removed from the C-terminal of the original peptide, respectively.
- a mixture containing a series of reaction products is obtained.
- mass spectrometry is applied to the mixture containing the series of reaction products to measure the mass of the ion species derived from each reaction product, a series of peaks showing a mass difference reflecting the C-terminal amino acid sequence Can be measured.
- each reaction product is generated from the original peptide in a sequential C-terminal amino acid degradation reaction, for example, from the original peptide to a reaction product in which several amino acid residues have been removed from the original peptide.
- mass spectrometry for a series of several reaction product groups, the masses of the corresponding ionic species can be analyzed collectively, and the C-terminal amino acid for such several amino acid residues Sequences can be determined collectively.
- C-terminal amino acids used for the preparation of nucleic acid probes and primers The sequence information is usually a base sequence encoding a powerful amino acid sequence, having a length of about 18 to 24 bases, and thus may have about 6 to 8 amino acids, and may have about 10 amino acids. It is only necessary in very special cases to elucidate the C-terminal amino acid sequence that reaches Therefore, the above-mentioned perfluoroalkanoic acid or perfluoroalkanoic anhydride vapor is supplied from the gas phase and is allowed to act on the dried peptide, thereby performing a sequential C-terminal amino acid decomposition reaction. For example, these means of preparing a processed sample containing a series of reaction products simultaneously to achieve the removal of 10 amino acid residues are adapted for the above-mentioned applications. Disclosure of the invention
- the molecular weight of the original peptide itself exceeds the molecular weight range applicable to mass spectrometry, or Since the change in the formula weight of one amino acid residue is relatively small compared to the large molecular weight of the peptide itself, and the measurement accuracy of the molecular weight difference is reduced, the following measures have been studied. Specifically, a series of reaction products in which 1 to 10 amino acid residues have been removed from the C-terminus of the original peptide obtained by the selective decomposition reaction of the C-terminal amino acid described above.
- a mixture containing the following was digested enzymatically with a long peptide chain using a protease with cleavage site specificity, such as trypsin, capable of selective cleavage of peptide chains at specific amino acid sites.
- a protease with cleavage site specificity such as trypsin
- the form of performing mass spectrometry on the peptide fragment is used.
- the mixture of peptide fragments obtained by vigorous enzymatic digestion contains a C-terminal peptide fragment derived from the original peptide and, in contrast, 1 to 10 amino acid residues.
- the above-described technique of supplying perfluoroalnic acid or perfluoroalnic acid anhydride vapor from the gas phase and acting on the dried peptide is a useful means for elucidating the C-terminal amino acid sequence
- the peptide to be analyzed is, for example, a peptide having a large number of amino acid residues such as a protein, it has been found that some practical problems described below remain when the method is used as a general-purpose means.
- the first problem is that, using the above-mentioned high-concentration aqueous solution of perfluoroalkanoic acid, for example, while heating to 90 ° C and allowing perfluoroalkanoic acid vapor to act on the dried peptide, ⁇ , ⁇ -acyl rearrangement between the ⁇ -amino group (1 ⁇ -) and the hydroxy group (1 ⁇ ) in the serine residue (1-NH—CH (CH 2 OH) -CO-)
- the reaction also proceeds, followed by hydrolysis, and there is a side reaction that peptide cleavage occurs at the terminal side of the serine residue.
- the second problem is that if the peptide to be analyzed is a peptide with a large number of amino acid residues, such as a protein, the cleavage site specific after performing the selective degradation reaction of the C-terminal amino acid It has been considered to add an enzyme digestion treatment using a protease having a property to measure the molecular weight of the resulting C-terminal peptide fragment. A plurality of N-terminal peptide fragments by-produced will be simultaneously observed on the measured mass spectrometry spectrum. In other words, the peaks derived from the original peptide and C-terminal peptide fragments derived from a series of reaction products and the peaks derived from other N-terminal peptide fragments were separated with high accuracy.
- the present invention solves the above-mentioned problems, and an object of the present invention is to sequentially convert the above-mentioned C-terminal amino acid of a long peptide chain by utilizing a reaction mechanism via formation of an oxazolone ring structure.
- An object of the present invention is to provide a method that can more easily analyze the C-terminal amino acid sequence of a! /, Peptide chain.
- the present inventors have conducted intensive studies and studies in order to solve the above-mentioned problems.As a result, using a high concentration aqueous solution of perfluoroalkanoic acid, for example, drying while heating to 90 ° C.
- the present inventors have developed a highly reactive reagent such as perfluoroalkanoic anhydride without using an aqueous solvent as a source of water molecules into the system.
- a highly reactive reagent such as perfluoroalkanoic anhydride
- an aqueous solvent as a source of water molecules into the system.
- a C-terminal amino acid to form an oxazolone ring structure as a reaction intermediate, followed by the cleavage of the oxazolone ring
- searching for reaction conditions capable of performing a selective decomposition reaction of terminal amino acids using a mixture of a small amount of perfluoroalkanoic acid added to arnic acid anhydride, for example, From the phase, the vaporized perfluorinated arnic acid and arnic acid anhydride, supplied from this mixture, are allowed to act on the dried peptide, for example, even at processing temperatures below 60 ° C.
- alkanoic anhydrides are much more moderately reactive than perfluoroalkanoic anhydrides. I also found that it was not possible.
- the N-acylation reaction to the N-terminal amino group proceeds, and the amino group at the ⁇ -position of the lysine residue (one NH—CH (CH 2 CH 2 CH 2 CH 2 NH 2 ) —CO—) N-acylation reaction of tyrosine residue (one NH—CH (CH 2 -C 6 H 4 -OH) -CO-) to phenolic hydroxy group also progresses. Also turned out.
- reactive functional groups such as hydroxyl groups and amino groups on the side chains involved in rearrangement reactions such as N, O-acyl rearrangement reactions, which induce peptide cleavage in the middle, are protected and modified.
- an oxazolone ring structure is formed from the target C-terminal amino acid as a reaction intermediate, and only the decomposition reaction of the C-terminal amino acid accompanying the cleavage of this oxazolone ring is continued.
- the treatment proceeds selectively at a processing temperature of 60 ° C or lower.
- the present inventors have made use of the above-mentioned perfluoroalkanoic acid and alkanoic anhydride to form an oxazolone ring structure, followed by selective cleavage of the C-terminal amino acid accompanying cleavage of this oxazolone ring.
- water molecules are not present in the system, and perfluoroalkanoic acid and alkane are contained in a dipolar aprotic solvent.
- the gel electrophoresis even if the peptide is carried on such a gel carrier, it is subjected to a dehydration treatment for sufficiently removing the water impregnated in the gel carrier, and then the dipolar aprotic
- a solution prepared by dissolving perfluoroalkanoic acid and alkanoic anhydride in a solvent is immersed in the gel carrier and the gel is swelled, the same liquid phase reaction occurs in the gel carrier. was found to be able to achieve.
- the present inventors are involved in a rearrangement reaction such as N, O-acyl rearrangement reaction, which induces premature cleavage of a peptide due to diacylation to a hydroxy group and N-acylation to an amino group.
- a rearrangement reaction such as N, O-acyl rearrangement reaction
- reactive functional groups such as hydroxy group and amino group on the side chain
- formation of oxazolone ring structure using perfluoroalkanoic acid and alkanoic anhydride as described above.
- performing a selective decomposition reaction of the C-terminal amino acid accompanying the cleavage of the oxazolone ring was more effective in avoiding unnecessary side reactions.
- Supply When the vaporized alkanoic anhydride and alkanoic acid are allowed to react with each other, an amino group at the N-terminus of the peptide and an amino acid at a side chain of a lysine residue which may be contained in the peptide are obtained. It has been found that the group can be subjected to N-acylation with an acyl group derived from the alkanoic anhydride and O-acylation to a hydroxy group on a side chain in advance.
- the peptide is carried on the gel carrier, it is subjected to a dehydration treatment to sufficiently remove the water impregnated in the gel carrier, and then the alginate is placed in a dipolar aprotic solvent.
- a solution prepared by dissolving the acid anhydride is immersed in the gel carrier to swell the gel, and the N-acylation and O-acylich reaction can be performed in the same liquid phase even in the gel carrier. Found that it is possible.
- the present inventors have also formed a oxazolone ring structure, and subsequently, a reactive intermediate associated with the cleavage of this oxazolone ring remains. It is necessary to subject the intermediate to a hydrolysis treatment to restore the C-terminus of the reaction product to a form in which a carboxy group is exposed, for subsequent mass spectrometry.
- the peptide chain of the reaction product generated by the decomposition reaction of the C-terminal amino acid also has the amino group at the N-terminal thereof and the amino acid at the side chain of lysine residue which may be contained in the peptide chain.
- the group will have N-acylation protection.
- amino groups on the side chains of lysine residues that may be contained in the peptide chain include:
- tryptic digestion When tryptic digestion is applied to a long peptide chain protected by N-acylation, trypsin digestion at the C-terminal peptide bond of lysine or arginine residue results in the specificity of lysine residue in the cleavage site specificity of trypsin.
- the amino group of the side chain is protected by N-acylation, and the peptide chain is not digested at the N-acylated lysine residue, and the resulting peptide fragment is not digested by arginine residue.
- the average frequency of arginine residues contained in the peptide chain for example, in a long peptide chain of about 200 amino acids, at least 4 or more, at most about 10 Only one arginine residue is present, and the above-mentioned C-terminal contains one arginine residue.
- the number of common peptide fragments is about 4 to 10, and the C-terminal side derived from the original peptide chain.
- the present inventors have conceived that the likelihood that the number of amino acids in the peptide fragment is in the range of at least 15 amino acids to 50 amino acids is considerably high.
- the present inventors have developed MALD I-TOF-MS (Matri Assisted Laser Desorption Ionization Time-of-Flight Mass Spectrometer try; When using a desorption ionization time-of-flight mass spectrometry method to measure the molecular weight of the cation species generated by the ionization treatment and the molecular weight of the anion species, a cation-like amino acid residue at the C-terminus
- the peak intensity in the molecular weight measurement with a cationic species is significantly higher than the corresponding peak intensity in the molecular weight measurement with an anionic species, while the cathodic at the C-terminus Naa
- the general trend is that the peak intensity in molecular weight measurements with anionic species is significantly larger than the corresponding peak intensity in molecular weight measurements with cationic species.
- a common peptide fragment containing one arginine residue at the C-terminus obtained by trypsin digestion is observed as a single peak with a large relative intensity in the measurement of molecular weight by cationic species.
- the peak intensity corresponding to the force and the common peptide fragment is relatively weak, but it can be easily identified by comparing the measurement results of the two, so the reverse.
- a series of peaks observed with a large relative intensity were derived from the original peptide chain derived from the partial amino acid sequence at the C-terminal side and containing no arginine residue.
- a group of C-terminal peptide fragments derived from the peptide chain of the reaction product can be easily identified as showing a series of peaks.
- one arginine residue is contained at the C-terminus.
- the common peptide fragment is discriminated from the original peptide chain containing no arginine residue and a group of C-terminal peptide fragments derived from the peptide chain of a series of reaction products.
- the present invention has the above-mentioned technical idea commonality, the present invention has a plurality of forms in which specific forms differ due to the existence state of the target peptide chain.
- the first form to be applied when the peptide to be analyzed is a previously isolated dry sample, and the peptide to be analyzed must be separated by gel electrophoresis in advance.
- the second embodiment is applied to a case where the sample is supported on the gel carrier.
- the method for analyzing the C-terminal amino acid sequence of a peptide according to the first embodiment of the present invention is a method for analyzing the C-terminal amino acid sequence of a peptide to be analyzed, comprising the steps of: Preparing a mixture containing a series of reaction products obtained by sequentially decomposing the C-terminal amino acid by means;
- the molecular weight difference between the series of reaction products and the original peptide was determined by mass spectrometry. Analyzing the C-terminal amino acid to sequentially reduce the molecular weight,
- N-acylation of an amino group at the N-terminus of the peptide and an amino group of a side chain of a lysine residue which may be contained in the peptide with an acyl group derived from the alkanoic anhydride A pretreatment step of applying N-acylation protection; and drying the N-acylation-protected dry sample of the peptide of interest at 15 ° C to 60 ° C under a dry atmosphere. At the temperature selected for the range,
- R 1 represents the side chain of the C-terminal amino acid of the peptide
- R 2 represents a side chain of an amino acid residue located immediately before the C-terminal amino acid), and the C-terminal amino acid is decomposed with the cleavage of the 5-oxazolone ring.
- trypsin is allowed to act, and the N-acyl is reacted with the amino group at the N-terminus of the peptide chain and the amino group of the side chain of the lysine residue that may be contained in the peptide chain.
- a digestion treatment specific to the trypsin enzyme which retains the protection of the peptide, by selective cleavage of the C-terminal peptide bond of the arginine residue present in the peptide chain.
- a step of performing peptide fragmentation subjecting to desalting, removing the buffer solution component, collecting the tryptic digested peptide fragment, and drying.
- the dried mixture containing the recovered tryptic digested peptide fragments is subjected to molecular weight measurement using a cation species generated in the ionization treatment, and using a negative ion species. Perform molecular weight measurement,
- the intensity in the molecular weight measurement by the cation species is determined to be a peak that gives a relatively large intensity compared to the intensity in the molecular weight measurement by the anion species, and is determined as the original peptide generated in the trypsin digestion treatment.
- the peak of the C-terminal peptide fragment derived from a series of reaction products obtained by sequentially decomposing the C-terminal amino acid is as follows:
- the intensity in the molecular weight measurement using the anion species is determined to be a peak giving a relatively large intensity as compared with the intensity in the molecular weight measurement using the cation species, and the intensity is relatively large in the molecular weight measurement using the anion species.
- a symmetrical acid anhydride of alnic acid having 2 to 4 carbon atoms is used as the alkynic anhydride contained in the mixture obtained by adding a small amount of perfluoroalkanoic acid to the above-mentioned alkynic anhydride.
- a symmetrical acid anhydride of alnic acid having 2 to 4 carbon atoms is used.
- acetic anhydride as the alkanoic anhydride contained in the mixture obtained by adding a small amount of perfluoroalkanoic acid to the alkanoic anhydride.
- the pKa of the perfluoroalkanoic acid is 0. It is preferred to use a perfluoroalkanoic acid in the range of 3-2.5. At this time, it is more preferable to use perfluoroalkanoic acid having 2 to 4 carbon atoms as perfluoroalkanoic acid contained in the mixture obtained by adding a small amount of perfluoroalkanoic acid to the alkanoic anhydride. preferable.
- a linear perfluorocarbon having 2 to 4 carbon atoms may be used. It is more preferable to use a fluoroalkanoic acid.
- the content ratio of perfluoroalkanoic acid is such that alkanoic anhydride and perfluoroalkanoic acid are contained. It is desirable to select from the range of 1 to 20% by volume based on the total volume of
- the drying atmosphere is more preferably a state in which oxygen has been removed in addition to moisture.
- the above-mentioned dry atmosphere is achieved by evacuating the atmosphere inside the airtight container.
- the temperature is more preferably set to a temperature selected from the range of 15 ° C to 50 ° C. .
- the method for analyzing the C-terminal amino acid sequence of a peptide according to the second aspect of the present invention comprises:
- a method for analyzing the C-terminal amino acid sequence of a peptide to be analyzed in which a mixture containing a series of reaction products obtained by sequentially decomposing C-terminal amino acids by chemical means is prepared from the target peptide.
- the gel sample is subjected to the gel-form at a temperature selected from the range of 30 ° C. to 80 ° C. with respect to the target peptide sample supported on the gel carrier.
- the gel carrier is immersed in the alkanoic anhydride solution using a solution obtained by dissolving the alkanoic anhydride in a dipolar aprotic solvent that can be infiltrated into a substance and can be maintained in a swollen state.
- the alkanoic anhydride is allowed to act on the peptide sample of interest in the supported state, and the amino group at the N-terminus of the peptide of interest and the possibility of being contained in the peptide
- the amino group on the side chain of the lysine residue is previously subjected to N-acylation protection by an acyl group derived from the alkanoic acid constituting the alkanoic anhydride,
- a temperature selected from the range of 30 ° C. to 80 ° C. is applied to the target peptide sample supported on the gel carrier.
- Perfluoroalkanoic acid is dissolved in a dipolar non-protonic solvent that can infiltrate into the gel-like substance and can be maintained in a swollen state at a ratio of a small amount to arnic anhydride.
- the gel carrier is immersed in the mixed solution using the mixed solution prepared as described above, whereby the alkanoic anhydride and the perfluoroalnic acid are allowed to act on the target peptide sample in a supported state.
- R 1 represents the side chain of the C-terminal amino acid of the peptide
- R 2 represents a side chain of an amino acid residue located immediately before the C-terminal amino acid).
- the mixed solution used for the sequential decomposition reaction of the C-terminal amino acid is mixed with the perfluoroalkanoic acid and the alkanoic acid anhydride and the dipolar aprotic solvent without causing the gel-like substance to dissolve.
- a mixture containing a series of reaction products obtained by a reaction for sequentially decomposing the C-terminal amino acid is reacted with a basic nitrogen-containing aromatic ring compound or a third nitrogen-containing compound while being supported on the gel carrier.
- a water molecule is allowed to act on the reaction product peptide in the coexistence of the basic nitrogen-containing organic compound, and the water treatment is performed.
- the re-dehydration treatment is performed, and then the mixture containing the series of hydrolyzed reaction products is supported on the gel carrier. Then, trypsin dissolved in the buffer solution is allowed to act on the N-terminal amino group of the peptide chain and the N-amino group on the side chain of the lysine residue which may be contained in the peptide chain.
- a peptide obtained by subjecting the peptide chain to a trypsin-enzyme-specific digestion treatment, which retains the acylyl protection, by selectively cleaving the C-terminal peptide bond of the arginine residue present in the peptide chain Perform fragmentation,
- the peptide fragment is released from the gel carrier and eluted into the buffer solution. Thereafter, desalting treatment is performed to remove the buffer solution component, and the trypsin digested peptide fragment is recovered. , Drying process is provided, Next, using the MA LDI-TOF-MS method, measuring the molecular weight of the recovered dry mixture containing the tryptic digested peptide fragment by the ionic species generated by the ionization treatment, and measuring the molecular weight by the anionic species Perform molecular weight measurement,
- the peak of a peptide fragment having an arginine residue at the C-terminus generated by the trypsin digestion treatment is as follows:
- the intensity in the molecular weight measurement by the ionic species is determined to be a peak giving a relatively large intensity as compared with the intensity in the molecular weight measurement by the anionic species, and the intensity is determined by the original peptide generated by the trypsin digestion treatment.
- the peaks of the C-terminal peptide fragment derived from the C-terminal peptide fragment and the C-terminal peptide fragment derived from a series of reaction products obtained by sequentially decomposing the C-terminal amino acid are as follows:
- the intensity in the molecular weight measurement by the anionic species is determined to be a peak giving a relatively large intensity as compared with the intensity in the molecular weight measurement by the cation species, and the intensity is relatively large in the molecular weight measurement by the anionic species.
- alkanoic anhydride contained in the mixed solution obtained by dissolving the perfluoroalkanoic acid in a small ratio with respect to the alkanoic anhydride a symmetrical acid of alkanoic acid having 2 to 4 carbon atoms is used. It is preferred to use an anhydride. In this case, it is more preferable to use a symmetrical acid anhydride of a straight-chain alkanoic acid having 2 to 4 carbon atoms as the symmetrical acid anhydride of the alkanoic acid having 2 to 4 carbon atoms.
- acetic anhydride as the alkanoic anhydride contained in the mixed solution obtained by dissolving the perfluoroalkanoic acid in a small amount with respect to the arnic anhydride.
- the perfluoroalnic acid is in a small amount relative to the anhydride of arnic acid.
- perfluoroalkanoic acid contained in the mixed solution obtained by dissolving at a ratio perfluoroalkanoic acid having a pKa of the perfluoroalkanoic acid in the range of 0.3 to 2.5 is used. Is preferred.
- perfluoroalkanoic acid contained in the mixed solution obtained by dissolving the perfluoroalkanoic acid in a small amount ratio with respect to arnic acid anhydride perfluoroalkanoic acid having 2 to 4 carbon atoms is used. It is preferred to use loalkanoic acids. In this case, it is more preferable to use a linear perfluoroalkanoic acid having 2 to 4 carbon atoms as the perfluoroalkanoic acid having 2 to 4 carbon atoms.
- the content ratio of alkanoic anhydride and perfluoroalkanoic acid in the mixed solution obtained by dissolving the perfluoroalkanoic acid in a small ratio with respect to the alkanoic anhydride is as follows. More preferably, it is selected in the range of 1 to 20 volumes of perfluoroalkanoic acid per 100 volumes of the product.
- FIG. 1 is a diagram showing a process flow illustrating an example of a detailed operation procedure for a peptide dried sample in a process of sequentially decomposing a C-terminal amino acid from a peptide according to the first embodiment of the present invention. It is.
- FIG. 2 shows an example of a detailed operation procedure for a peptide sample supported on a gel in a process for sequentially decomposing a C-terminal amino acid from a peptide according to the second embodiment of the present invention. It is a figure showing the process flow illustrated.
- FIG. 3 shows that the C-terminal amino acid of the globin-peptide chain of a dried sample of poma 'myoglobin was determined according to the treatment method for sequentially decomposing the C-terminal amino acid from the peptide according to the first embodiment of the present invention.
- FIG. 3 is a diagram showing an example of a mass spectrometry spectrum obtained by measuring a peptide fragment obtained by digesting a reaction product mixture obtained by sequentially decomposing the mixture into a tryptic digest in a cation species detection mode using a MA LDI-TOF-MS device. .
- FIG. 4 shows the results for a dried sample of Puma 'myoglobin according to the treatment method for sequentially decomposing C-terminal amino acids from peptides according to the first embodiment of the present invention.
- the peptide fragment obtained by trypsin digestion of the reaction product mixture obtained by sequentially decomposing the C-terminal amino acid of the globin-peptide chain was measured in an anion species detection mode using a MA LDI-TOF-MS device
- FIG. 3 is a diagram illustrating an example of a mass spectrometry spectrum.
- FIG. 5 is a graph showing the results of a method for sequentially decomposing C-terminal amino acids from a peptide according to the second embodiment of the present invention.
- the globin peptide chain C Peptide fragments obtained by tryptic digestion of the reaction product mixture obtained by sequentially decomposing the terminal amino acids were analyzed by mass spectrometry using a MA LDI-T ⁇ F-MS device in a cationic species detection mode. It is a figure which shows an example of a knotnore.
- FIG. 6 shows a globin-peptide chain of a poma myoglobin sample supported on a gel according to a treatment method for sequentially decomposing a C-terminal amino acid from a peptide according to the second embodiment of the present invention.
- the peptide fragment obtained by tryptic digestion of the reaction product mixture obtained by sequentially decomposing the C-terminal amino acid of the above was analyzed by mass spectrometry using a MA LDI-TOF-MS device in an anion species detection mode. It is a figure showing an example of a vector.
- Figure 7 shows the trypsin cleavage site at the C-terminal peptide bond of arginine residues and N-acetylation protection, which is contained in the amino acid sequence of the globin peptide chain, which composes pima'myoglobin. Indicates a lysine residue that is prevented from being cleaved at the C-terminal peptide bond when applied.
- FIG. 7 is a diagram showing a comparison between mass spectrometry spectra measured in the () and cation species detection modes (top).
- the method for analyzing the C-terminal amino acid sequence of a peptide according to the present invention is basically a method of shortening the peptide by sequentially removing the C-terminal amino acid of the peptide to be analyzed from the peptide to be analyzed.
- a series of reaction products and further, of the peptide fragments obtained by tryptic digestion of the series of reaction products and the original peptide, of the c-terminal peptide fragment derived from the series of reaction products
- a method for identifying the removed amino acids is adopted.
- the C-terminal peptide fragment obtained by digestion with such trypsin is cleaved at a cleavage site specific to the trypsin, and further, the C-terminal derived from this series of reaction products.
- a MA LDI_TOF-MS device is used as a means of measuring the molecular weight of the side peptide fragment and the molecular weight of the C-terminal peptide fragment derived from the original peptide. This makes it possible to measure the cationic species to which (H +) is added and the anionic species from which the proton (H +) has been released from the peptide fragment.
- the amino acid residues constituting the C-terminal peptide fragment do not contain arginine residues or lysine residues, the cationic species derived from such arginine residues or lysine residues are not included. There is no stabilization mechanism.Comparing the results of measurement of cationic species with those of anionic species, trypsin contains arginine and lysine residues in amino acid residues. The relative intensities of the other peptide fragments by digestion are different from that of the other peptide fragments. A series of C-terminal peptides were detected from multiple peaks measured by the MA LDI-T ⁇ F-MS instrument. Identification of peaks caused by fragments ⁇ Used for discrimination.
- the biggest feature of the analysis method according to the present invention is that
- the peptide is obtained after the trypsin digestion treatment. Except for the common N-terminal peptide fragment and the C-terminal peptide fragment derived from the desired series of reaction products, which are generated when the original peptide is digested with h-ribsin in the mixture of peptide fragments, To the secondary Another object of the present invention is to prevent contamination of peptide fragments derived from the peptide bond cleavage reaction.
- the target peptide chain is protected by N-acylation and O-acylation in advance, and Utilize the protection and, prior to the final trypsin digestion treatment, deprotect the protection by monoacylation, but retain the N-acylation protection on the lysine residue. In this way, fragmentation due to trypsin digestion occurs only at the C-terminal peptide bond of the arginine residue, thereby avoiding the generation of unnecessarily fragmented peptide fragments.
- An important feature of the analysis method according to the present invention is that the derived C-terminal peptide fragment can be within a molecular weight range suitable for MALDI-TOF-MS measurement.
- the reaction used in the present invention for sequentially decomposing and removing the C-terminal amino acid of the target peptide is performed under a relatively low heating condition under an environment with water removed.
- the alkanoic anhydride is catalyzed by perfluoroalkanoic acid, which exhibits high proton donating ability.
- Act as a reagent for activating the C-terminal carboxy group of the peptide chain
- R 1 represents the side chain of the C-terminal amino acid of the peptide
- R 2 represents a side chain of an amino acid residue located immediately before the C-terminal amino acid), and forms a 5-oxazolone structure, and the C-terminal amino acid is It uses a method of performing decomposition.
- the reaction of the formation of the 5-oxazolone ring, as a whole, is represented by the reaction formula (I):
- the perfluoroalkanoic acid present in a small amount is made to function as a proton donor with respect to the dried peptide, thereby increasing the ratio of the enol form.
- an alkanoic anhydride is used as a reagent for activating a C-terminal carboxy group.
- the reaction represented by the reaction formula ( ⁇ ) can be carried out, for example, from the formed 5-oxazolone ring:
- the serine residue in a peptide chain (an NH- CH (CH 2 OH) -CO- ), a threonine residue (- NH- CH (CH (CH 3) OH) -CO-)
- the amino group at the ⁇ ; position (1- ⁇ ) of a serine residue (1-NH—CH (CH 2 OH) —CO—) due to the hydroxyl group (-1 OH)
- the ester bond formed continues to be decomposed, and the peptide is cleaved at the N-terminal side of the serine residue.
- the sequential C-terminal amino acid decomposition reaction is carried out in a dry state under mild temperature conditions, the above-mentioned serine residue (— ⁇ —CH (CH 2 OH) —CO—) and threonine residue
- the side reaction involving the group one NH—CH (CH (CH 3 ) OH) —CO—) and the lysine residue (one NH—CH (CH 2 CH 2 CH 2 CH 2 NH 2 ) -CO-)
- a pre-treatment step for protection by N-acylation and O-acylation is provided before the sequential C-terminal amino acid degradation reaction.
- the dry sample of the peptide of interest is subjected to drying at 10 ° C. to 6 ° C. in a dry atmosphere.
- the alkane anhydride is allowed to act by reacting the alkanoic anhydride with the alkanoic acid, which is supplied from a mixture obtained by adding a small amount of alkanoic acid to the alkanoic anhydride.
- the peptide sample supported on the gel is subjected to a dehydration treatment of the gel in advance, and in this pretreatment step, Dissolving the alkanoic anhydride in a dipolar, non-protonic solvent capable of infiltrating into the gel-like material and maintaining a swelling state at a temperature selected in the range of 0 ° C. to 80 ° C.
- the gel carrier is immersed in the alkanoic anhydride solution using a solution comprising Achievement and achievability.
- the liquid phase reaction in the dipolar aprotic solvent proceeds sufficiently without using the acid catalysis of an alkanoic acid having a proton donating ability.
- alkanoic acid is generated in the system, the catalytic action is added, and the reaction is gradually promoted.
- the proton-donating ability of the alkanoic acid derived in the system is inferior to the proton-donating ability of perfluoroalkanoic acid. Does not lead to
- the amino group ( ⁇ 2 ) at the ⁇ -position of the lysine residue (NHNH—CH (CH 2 CH 2 CH 2 CH 2 NH 2 ) —CO—) is added with a calorie.
- the amino group ( ⁇ 2 ) at the ⁇ -position of the lysine residue (NHNH—CH (CH 2 CH 2 CH 2 CH 2 NH 2 ) —CO—) is added with a calorie.
- the amino group at the ⁇ -position of the lysine residue ((-CH (CH 2 CH 2 CH 2 CH 2 NH 2 ) -CO-) ( ⁇ 2 )
- ⁇ -acylation protection of the amino group at the ⁇ -terminal of the peptide chain as a result of selecting hydrolysis treatment conditions that do not cause deprotection
- trypsin digestion the amino group on the side chain
- the enzymatic digestion reaction by trypsin does not proceed, and the peptide fragment obtained by trypsin digestion is obtained by digestion at the C-terminal side of arginine residues.
- the amino group on the side chain of the lysine residue is subjected to a trypsin digestion treatment in a state where the amino group is protected for the acylation, whereby the peptide chain is Digested at two cleavage sites, arginine residue and lysine residue, Long peptide chains can be split into multiple peptide fragments by tryptic digestion of arginine residues, which are contained in the peptide chains at a moderate frequency, while avoiding unnecessary fragmentation.
- the advantage that the molecular weight of the obtained C-terminal peptide fragment can be within the molecular weight range suitable for MALDI-TOF-MS measurement is positively utilized.
- the present invention it is obtained by subjecting to trypsin digestion, desalting, collecting peptide fragments, drying and subjecting to trypsin digestion using a MA LDI-TOF-MS device. Measure the molecular weight of the ionic species from the mixture of peptide fragments.
- the peptide fragments recovered and dried by desalting after trypsin digestion do not form various salts, but are used as the original peptide portion alone.
- a cation species to which a proton (H +) has been added and an anion species to which a proton (H +) has been released can be generated for each peptide fragment. Ion species and anion species are measured separately.
- the peptide fragment generated by trypsin digestion is derived from the N-terminal amino acid sequence common to the original peptide chain and the reaction product generated by the sequential decomposition reaction of the C-terminal amino acid.
- an arginine residue with a guanidino group rich in proton (H +) receptivity exists at the C-terminus of the fragment, stabilizing the cationic species to which proton (H +) is added.
- an arginine residue is not present, and stabilization of a cationic species to which a proton (H +) is added due to the arginine residue does not occur.
- the fragment in the mass spectrometry spectrum of the cationic species which is measured with a MA LDI-TOF-MS instrument, has an arginine residue at the C-terminal of the fragment, and has a common N-terminal.
- the peak intensity derived from a series of peptide fragments derived from the amino acid sequence becomes relatively strong.
- a carboxy group (one COOH) capable of donating a proton (H +) exists at the C-terminus, and it was measured using a MA LDI-TOF-MS instrument.
- the peak intensity attributable to the C-terminal peptide fragment group 200 degrees is relatively strong.
- the desalted and dried peptide fragment is subjected to measurement with a MA LDI-TOF-MS device, and the mass spectrometry of the cation species and the spectrum of the anion species are performed.
- mass spectrometry of the cation species and the spectrum of the anion species are performed.
- a series of peptide fragments derived from a common N-terminal amino acid sequence having an arginine residue at the C-terminus The peak due to the group is discriminated, and in the mass spectrometry spectrum of the anionic species, the N-terminal side common to the original peptide chain and the reaction product generated by the sequential decomposition reaction of the C-terminal amino acid Peaks derived from a series of C-terminal peptide fragments derived from the amino acid sequence can be easily identified.
- C-terminal, side peptide fragments not exist according arginine residues, at least, by trypsin digestion process, has its N-terminal amino acid amino groups of the ⁇ -position residue (one ⁇ 2) Since the corresponding peak is also shown on the mass spectrometry spectrum of the cation species, the assignment result of the amino acid type is determined by using the molecular weight of the corresponding peak observed in the mass spectrometry spectrum of the cation species. Can also be verified.
- the method for analyzing the C-terminal amino acid sequence of a peptide according to the first embodiment of the present invention corresponds to (1) to (3) in the steps (1) to (6) characterizing the present invention described above.
- a dry sample of the peptide that has been subjected to isolation processing in advance is used. The following processing is performed for
- a pretreatment step of applying N-acylation to the amino group on the side chain of the residue with an acyl group derived from the alkanoic anhydride and performing N-acylation protection is performed.
- the N-acylation protection for the amino group of the side chain of lysine residue, which is performed in this pretreatment step, is described above.
- the N-acylation protection on the lysine residue side chain does not proceed with deprotection, but the O-acylation protection performed simultaneously It is desirable to select an acyl group for which deprotection proceeds sufficiently.
- a reaction in which a dried sample of a peptide can be supplied as a vapor from a gaseous phase to perform N-acylation that is, an O-acylation reaction.
- a combination of an alkanoic anhydride as an electrophilic acylating agent as a reagent and an alkanoic acid as a catalyst for promoting the acylation reaction by its proton donating ability is used.
- the arnic acid anhydride and arnic acid used in this pretreatment step are supplied as steam at a constant partial pressure ratio under a dry atmosphere to act on the peptide chain, and thus are kept in an airtight state.
- the entire reaction vessel is heated and kept at a temperature selected in the range of 10 ° C to 60 ° C to evaporate from a mixture of alkanoic anhydride and a small amount of alkanoic acid added.
- a straight-chain alkanoic acid having 2 to 4 carbon atoms and a symmetrical anhydride derived from the straight-chain alkanoic acid having 2 to 4 carbon atoms is more preferably a symmetrical anhydride derived from alkanoic acid added in a small amount. That is, if the alkanoic anhydride and the alkanoic acid added in a small amount are of the same species, even if an acylation reaction occurs during the progress of the N-alkanoylation or O-alkanoylation reaction, Different alkanoyl groups are not mixed in the finally obtained N-alkanoylation and O-alkanoylation protection.
- alkanoic anhydride and alkanoic acid are supplied as vapor to a dry peptide sample to proceed with the reaction.
- the same arnic acid anhydride as the arnic acid anhydride used in the subsequent step of sequentially decomposing the C-terminal amino acid can be suitably used.
- this alkanoic anhydride under a dry atmosphere, at a temperature selected in the range of 10 ° C to 60 ° C, may cause unnecessary side reactions such as cleavage of the peptide by its reactivity. Is sufficiently low that, in vigorous pretreatment, the coexisting alkanoic acid has a much lower acid catalysis than perfluoroalkanoic acid, and thus causes unnecessary side reactions. Without this, it is possible to provide silation protection.
- a peptide having a long amino acid sequence of interest such as a protein
- a secondary structure or a tertiary structure a peptide that does not exhibit the multi-dimensional structure is subjected to a defolding process in advance.
- the amino group at the N-terminal is protected by N-acyluich by converting it into a chain
- the amino group of any side chain of lysine residue present in the peptide can be protected by N-acyluich.
- the hydroxyl group on the side chain of the serine residue and the threonine residue present in the peptide is protected by the disulfide reaction.
- the phenolic hydroxy group on the side chain of the tyrosine residue present in the peptide also has a different reactivity, but is partially oxidized.
- the amino group of the side chain of lysine residue, and the hydroxyl group of the side chain of threonine residue in the case of serine residue are all protected and modified. And no longer participate in unnecessary side reactions.
- the combination of alkanoic anhydride and alkanoic acid used in this pretreatment step may cause unnecessary side reactions such as cleavage in the middle of the peptide.
- the reaction temperature is selected to be in the range of 10 ° C to 60 ° C, and more preferably, the reaction temperature is in the range of about room temperature or slightly higher than room temperature. It is preferable to select within the range, more specifically, it is preferable to select within the range of 15 ° C. to 50 ° C. Further, in the mixture obtained by adding a small amount of alkanoic acid to the alkanoic anhydride, the addition ratio of alkanoic acid is 2 to 1 with respect to the total volume of alkanoic anhydride and alkanoic acid. It is preferable to select the range of 0% by volume, specifically, 5% by volume.
- the reaction rate of the N-acylation reaction in this pretreatment step depends on the partial pressure (gas phase concentration) of the alkanoic anhydride and alkanoic acid used and the reaction temperature. It is desirable that the time is appropriately selected mainly depending on the reaction temperature. For example, when selecting a reaction temperature of 50 ° C, complete the N-acylation of the N-terminal amino group of the peptide by selecting the reaction time within 1 hour, for example, 30 minutes. Is also possible.
- a catalytic amount of pyridine for example, 0.1 to 1.0 volume with respect to the total of the alkanoic anhydride and the alkanoic acid is used. It is more preferred to add% pyridine. Since such a pyridine base functions as a proton acceptor, for example, removal of a peptide to be eliminated with acylation to an amino group is performed more quickly.
- the peptide of interest forms, for example, an oxidized 1 S—S— bond with the cysteine of an adjacent peptide, or forms a 1 S—S— bond in the same molecule.
- a conventional reduction treatment is performed in advance to eliminate such cross-linking, and the peptide is converted to a peptide containing reduced cysteine.
- the reduced cysteine present in the peptide is protected in advance by subjecting the sulfanyl group (1SH) in its side chain to carboxymethylation and pyridylethylation.
- a peptide having a long amino acid sequence of interest such as a protein
- a defolding process in advance to obtain the multi-dimensional structure.
- a conventional reduction treatment is performed in advance to eliminate such cross-linking, and the peptide is converted to a peptide containing reduced cysteine.
- the reduced cysteine present in the peptide is protected in advance by subjecting the side chain sulfanyl group (-SH) to carboxymethylylation or pyridylethylation, etc.
- a liquid mixture obtained by adding a small amount of alkanoic acid to alkanoic anhydride was placed in a reaction vessel capable of forming an airtight state, and the liquid mixture was once cooled to lower the vapor pressure.
- the reaction vessel is evacuated, sealed, heated to the reaction temperature, and the alkanoic anhydride is evaporated in the vessel.
- Adopting a powerful procedure also has the advantage of preventing water from entering the reaction vessel.
- the amino acid present in methionine is oxidized by oxygen
- the reaction reagent remaining in the reaction vessel is removed, and then the process proceeds to the next reaction step in which the c-terminal amino acid is sequentially decomposed.
- the pretreatment step is followed by a dry atmosphere of the N-acylated protected peptide under a dry atmosphere.
- a temperature selected in the range of ° C to 60 ° C is selected in the range of ° C to 60 ° C.
- R 1 represents the side chain of the C-terminal amino acid of the peptide
- R 2 represents the side chain of the amino acid residue located immediately before the C-terminal amino acid), and the C-terminal amino acid is decomposed with the cleavage of the 5-oxazolone ring. .
- the vapor-form perfluoroalkanoic acid is allowed to function as a proton donor for the dried peptide, thereby increasing the ratio of the enol / re-form.
- an intramolecular ester bond is formed between the exposed hydroxy group and the C-terminal carboxy group to complete the 5-oxazolone ring.
- the vapor-like perfluoroalkanoic acid probably acts as a proton and a donor in this esterification reaction and induces an esterification reaction under an acid catalyst.
- an alkanoic anhydride is used as a reagent for activating a C-terminal carboxy group.
- reaction temperature can be selected in the range of 15 ° C to 60 ° C.
- the reaction temperature is preferably selected around room temperature or in a range slightly higher than room temperature, and more specifically, more preferably in the range of 15 ° C to 50 ° C.
- N-terminal amino group of the peptide is treated with the alkanoic anhydride. Since N-acylation usually occurs, N-acylation protection is performed in the system. However, it is more preferable to perform pretreatment for N-acylation protection in advance.
- the first embodiment of the present invention utilizes the high proton-donating ability of the perfluoroalkanoic acid used, and the pKa of the perfluoroalkanoic acid is 0.3 to 2 It is preferred to use a perfluoroalkanoic acid in the range of 5.
- the perfluoroalkanoic acid must be supplied as a vapor to the dried peptide sample, and at the temperature selected in the range of 15 ° C to 60 ° C, the desired vapor pressure Desirably, it is a perfluoroalkanoic acid which is excellent in volatility and can be obtained.
- perfluoroalkanoic acids having 2 to 4 carbon atoms are more suitable, and linear perfluoroalkanoic acids having 2 to 4 carbon atoms are more suitable.
- the alkanoic anhydride used as the above-mentioned activating reagent is not consumed according to the reaction, and therefore, the vapor pressure of the alkanoic anhydride supplied as a vapor state is used.
- the means there is a method in which the system in which the reaction is carried out is made airtight, and the vapor pressure of the alkanoic anhydride present in the system is stabilized. More specifically, a liquid mixture obtained by adding a small amount of perfluoroalkanoic acid to alkanoic acid anhydride is placed in a reaction vessel capable of forming an airtight state, and the liquid mixture is cooled and cooled. With the pressure reduced, the reaction vessel is evacuated, sealed, heated to the reaction temperature, and alkanoic anhydride is evaporated in the vessel. Adopting a powerful procedure also has the advantage of preventing water from entering the reaction vessel.
- alkanoic anhydrides can be used as long as they generate an appropriate vapor pressure when heated to the reaction temperature.
- the reaction temperature is selected within the above-mentioned preferable range, for example, a range of 15 ° C. to 50 ° C., it is preferable to provide a sufficient vapor pressure, and accordingly, an alkane having 2 to 4 carbon atoms is preferable. It is preferable to use a symmetrical acid anhydride.
- a symmetrical acid anhydride of a linear alkanoic acid having 2 to 4 carbon atoms as the symmetrical acid anhydride, and particularly, a symmetrical acid anhydride of a linear alkanoic acid having 2 carbon atoms.
- Acetic anhydride can be suitably used. Since such an alkanoic acid anhydride is used for activating the C-terminal carboxy group, it is preferable that the alkanoic acid anhydride does not cause steric hindrance at that time, and in that respect, acetic anhydride and the like described above are more preferable. .
- the alkanoic anhydride and perfluoroalkanoic acid used in this decomposition reaction are both vaporized and are allowed to act on the dried peptide sample.
- the 5-oxazolone ring once formed is The reaction is carried out in a dry atmosphere to avoid being hydrated and returned to the original state by the water that has entered from above. From this viewpoint, it is generally desirable to carry out such a reaction in a sealed reaction vessel.
- the mixture of alkanoic anhydride and perfluoroalkanoic acid initially supplied to the company is a liquid mixture at room temperature, and the alkanoic anhydride and perfluoroalkanoic acid are uniformly mixed. State.
- a mixture of this alkanoic acid anhydride and a small amount of perfluorinated alkanoic acid should be used in a small amount because the perfluoroalkanoic acid used as a catalyst is not consumed in principle during the reaction. Can be. More specifically, perfluoroalkanoic acid present as a vapor in the gas phase also means that it can have a relatively lower concentration compared to alkanoic anhydride which also exists as a vapor. . Conversely, depending on the type of alkanoic anhydride and perfluoroalkanoic acid used, the desired partial pressure ratio in the gas phase (gas phase concentration ratio) can be achieved, for example, according to its saturated vapor pressure at the reaction temperature. Use the liquid mixture at the mixing ratio appropriately.
- the content ratio of perfluoroalnic acid is the total volume of alkanoic anhydride and perfluoroalkanoic acid. Against 1 to 20 volumes. / 0 , more preferably in the range of 3 to 10% by volume.
- reaction formula ( ⁇ ⁇ ) for example, from the once formed 5-oxazolone ring:
- reaction (I) the elimination of the amino acid at the C-terminus and the formation of the reaction intermediate in the next step proceed, and the sequential selective decomposition of the amino acid at the C-terminus proceeds. Therefore, after the completion of such a reaction, the reaction product obtained is, besides the one having a carboxy group at the C-terminus shown in the above-mentioned reaction formula (II), a 5-oxazolone ring as an intermediate product Those that remain in the structure, or those in which the C-terminus has become an asymmetric acid anhydride as one form of the reaction intermediate, are also mixed.
- the reaction in such a sequential step of selectively decomposing the C-terminal amino acid is small.
- a two-step process of forming the 5-oxazolone ring structure exemplified by the reaction formula (I b) and separating the terminal amino acid by cleavage of the 5-oxazolone ring structure exemplified by the reaction formula ( ⁇ ) It consists of elementary reactions. Therefore, although the overall reaction rate depends on both of the reaction rates in each of these processes, the reaction rate mainly depends on the vapor partial pressure of the alkanoic anhydride and perfluoroalkanoic acid used (gas phase concentration) and the reaction temperature. Depends.
- the treatment time in such a sequential step of selectively decomposing the C-terminal amino acid mainly depends on the vapor partial pressure (gas phase concentration) of the alkanoic anhydride and perfluoroalkanoic acid to be used and the reaction temperature. In accordance with the above, it is appropriately selected in consideration of the target amino acid length of the C-terminal amino acid sequence to be analyzed.
- a compound having a form of a reaction intermediate in which a carboxy group is not expressed at the C-terminus as exemplified in the above reaction formula ( ⁇ ), which is generated in a sequential step of selectively decomposing a C-terminal amino acid is used.
- a water treatment step is provided as a post-treatment step in order to restore the form in which a carboxy group is exposed at the C-terminal. That is, in the first embodiment of the present invention, in the step of adding water, the residual force is applied to a mixture containing a series of reaction products obtained in the step of sequentially decomposing the C-terminal amino acid.
- the vapor-form basic nitrogen-containing aromatic ring compound or tertiary amine compound used for such a hydrolysis treatment reacts, for example, with a residue in which the C-terminus has reached an asymmetric acid anhydride to form an amide. This is preferable because no bond is formed and a uniform solution can be obtained when the solution is used as an aqueous solution.
- a monocyclic nitrogen-containing aromatic ring compound that can give an appropriate vapor pressure is preferable.
- pyridine can be more suitably used.
- the third Amin compounds available preferably has a relatively weak basicity and comparable basicity said pyridine base is shown, for example, DMA E ((CH 3) 2 N - CH 2 CH 2 OH) can be suitably used.
- DMA E ((CH 3) 2 N - CH 2 CH 2 OH)
- pyridine it is preferable to select pyridine in a range of 5 to 15% by volume, more specifically, 10% by volume, based on the total volume of the aqueous solution.
- DMAE dimethylamino) ethanol
- DMAE is used in an amount of 1 to 20% by volume, more specifically, 10% by volume, based on the total volume of the aqueous solution. It is preferable to choose
- a pretreatment step, a selective decomposition reaction step for a C-terminal amino acid, and a post-treatment step are performed in the same reactor. It is more preferable to carry out in a continuous form.
- An example of the flow of such a process is illustrated in FIG.
- each peptide sample is provided with a dry-up operation to prevent the reagent used in that process from remaining. This dry-up operation is generally performed by distillation under reduced pressure, and in that case, removal of decomposed terminal amino acids and the like derived by the reaction may be sometimes performed at the same time.
- FIG. 1 an example is shown in which acetic anhydride is used as the alkanoic acid anhydride of extremely high purity, which is easily available.
- the processing time in the step of selectively decomposing the C-terminal amino acid is 10 times as long as the amino acid length of the C-terminal amino acid sequence shortened during this step. It illustrates the range of treatment time that can be selected depending on the ratio of acetic anhydride and fluoroalkanoic acid to be used and the treatment temperature when targeting a few amino acids in length, or at least 3 amino acids in length. In general, when the ratio of fluoroalkanoic acid is increased and the processing temperature is set higher, the reaction rate is lower, and a shorter processing time is used to prepare a series of reaction products that achieve the longest target amino acid sequence shortening. Becomes possible.
- N-acetylation of the N-terminal amino group of the peptide is carried out using acetic anhydride and acetic acid in a vapor state, but in this combination of acetic anhydride and acetic acid.
- an active reaction of the C-terminal carboxy group represented by the above reaction formula (Ia) and a secondary reaction resulting therefrom may be induced.
- a small amount of pyridine vapor coexists, and the pyridine base forms a weak addition salt with the C-terminal carboxy group of the peptide, thereby protecting against unnecessary side reactions. It is possible to have an effect.
- this addition salt type is based on this pretreatment step. At the end of the process, a dry-up operation is provided, and the pyridine base is distilled off under reduced pressure, so that it is easily deprotected, causing problems in the subsequent step of the selective decomposition reaction of the C-terminal amino acid.
- a nitrogen-containing complex aromatic ring compound such as pyridine base
- the addition salt type protection has a protective function against the carboxy group of the amino acid side chain, it is also possible to simultaneously effectively suppress unnecessary side reactions caused by the carboxy group of the amino acid side chain. It becomes possible.
- the difference between the molecular weight of a series of reaction products prepared by the above-described sequential removal of the C-terminal amino acid and the molecular weight of the original peptide is determined by using the result of mass spectrometry. And determine the amino acid corresponding to the difference in molecular weight. Therefore, it is usually desirable that the original peptide remains in such a state that its molecular weight can be specified in the mixture subjected to the measurement by the mass spectrometry.
- the method for analyzing the C-terminal amino acid sequence of a peptide according to the first embodiment of the present invention is applied to the analysis of a C-terminal amino acid sequence up to about 10 amino acids in length.
- the content ratio of a series of reaction products corresponding to a maximum of several types corresponding to a maximum of 10 types should not be less than at least about 1/10 of the maximum content ratio. desirable.
- it is desirable that the residual amount of the original peptide is not less than at least about 1/10 with respect to the reaction product having the maximum content ratio.
- the required C-terminal amino acid sequence information is often within 10 amino acids, and if the treatment time is selected so that the decomposition of about 10 amino acids proceeds, the above-mentioned condition regarding the content ratio can be satisfied. You.
- the series of reaction products corresponding to (4) to (6) Analyzing the difference in molecular weight from the resulting peptide by mass spectrometry, and measuring the molecular weight decrease associated with the sequential degradation of the C-terminal amino acid; and a series of measured molecular weight decreases.
- the step of identifying a series of sequentially decomposed amino acids based on the small amount and arranging them from the C-terminus to obtain amino acid sequence information at the C-terminus will be described in further detail.
- the use of a MA LDI-TOF-MS device for the measurement of the molecular weight makes it possible to accurately measure the molecular weight of a high-molecular-weight peptide chain.
- MA LDI-TOF-MS equipment which is suitable for the measurement of high molecular weight molecules such as peptides
- the maximum possible amino acid length of the peptide does not exceed 30 to 50 amino acids.
- the corresponding amino acids are identified based on the difference in molecular weight, so that, for example, 311 and 5, and G111 and 0111, the difference in formula weight is 1 so that the amino acid residues can be distinguished from each other with high precision.
- the molecular weight of the reference, longest peptide, i.e., the peptide without the removal of the C-terminal amino acid, does not exceed 400, more preferably exceeds 300. It is more preferable that it is not in the range. When this is converted into an amino acid length, it is preferable that the length be at most 40 amino acids, more preferably a range not exceeding 30 amino acids.
- the cleavage amino acid sequence site is identified before performing mass spectrometry. Specific cleavage of the peptide chain using trypsin, which is a protease with excellent enzymatic reaction efficiency, and using the resulting C-terminal peptide fragment to obtain the C-terminal amino acid The difference between the molecular weight of a series of reaction products prepared by the sequential removal of the peptide and the molecular weight of the original peptide is measured.
- trypsin digestion treatment after the re-drying treatment, trypsin is allowed to act on the mixture containing the series of hydrolyzed reaction products in a buffer solution, and if the amino group at the N-terminal of the peptide chain is Next, the peptide chain is subjected to a trypsin enzyme-specific digestion treatment that retains N-acylation protection for the amino group of the side chain of a lysine residue that may be contained in the peptide chain. ing.
- the total number of peptide fragments obtained can reach a significant number, resulting in a shorter average amino acid length for each fragment and a narrower molecular weight range.
- peaks resulting from a considerable number of peptide fragments tend to be clustered. If peaks due to a considerable number of peptide fragments are clustered, it may be an obstacle in identifying a target group of C-terminal peptide fragments.
- the C-terminal peptide fragment derived from a series of reaction products in which the C-terminal amino acids are sequentially degraded the content ratio decreases as the number of amino acids removed increases.
- the presence of other peptide fragments can be a major obstacle in identifying the desired C-terminal peptide fragment.
- the total number of obtained peptide fragments may be increased more than necessary. It can be avoided, and at the same time, the amino acid length of the target C-terminal peptide fragment can be within the range of an appropriate number of amino acids when using the above-described MALDI-TOF-MS device.
- the dried mixture is subjected to molecular weight measurement using a cation species generated by the ionization treatment and molecular weight measurement using an anion species.
- the peak of the corresponding ionic species due to the arginine residue has an intensity of anion in the molecular weight measurement by the ionic species.
- C-terminal peptide fragments derived from the original peptide and the C-terminal amino acids, which are generated by trypsin digestion are determined sequentially. Since there is no arginine residue in the c-terminal peptide fragment derived from a series of reaction products obtained by decomposition, the peak of the corresponding ion species is as follows:
- the intensity in the molecular weight measurement using an anionic species is determined to be a peak that gives a relatively large intensity compared to the intensity in the molecular weight measurement using a cationic species
- leucine having the same formula amount is used to identify amino acids that are sequentially removed based on the difference in molecular weight.
- glutamine (G in) residue and the lysine (Ly s) residue have the same formula weight, N-alkanoylation is applied to the side chain of the lysine (Ly s) residue. Can be discriminated.
- alkanoic anhydride and perfluoroalkanoic acid are allowed to act.
- Serine residue in (one N H-CH (CH 2 OH) — CO—) Hydroxy group, N-terminal amino group, lysine residue (—) present in the threonine residue (one NH—CH (CH (CH 3 ) OH) -CO-) Do not carry out the pretreatment step of ⁇ -acylation and ⁇ -acylation protection for the amino group at the ⁇ -position of NH—CH (CH 2 CH 2 CH 2 CH 2 NH 2 ) -CO-) in advance. However, under the reaction conditions in which the strong C-terminal amino acid is sequentially degraded, these ⁇ -acylation and ⁇ -acylation reactions also proceed in parallel.
- the acetyl-substituted product may have been subjected to the amino acid removal described above.
- sufficient measures are taken to address such concerns by selecting conditions under which the deprotection of O-acylation protection at serine residues and threonine residues proceeds sufficiently in the hydrolysis treatment in the post-treatment step. I have.
- peptide fragmentation After the measurement of the molecular weight, the measured molecular weight is defined as the range in which the analytical accuracy can be determined so that the glutamine residue having a formula weight difference of 1 can be distinguished from the glutamic acid residue. The difference between the number of remaining acetyl groups and the number of amino acid residues having similar formula weights is 2-3, and in many cases, the possibility of such misidentification is eliminated.
- the liquid reagent for the reaction or the liquid reagent of the component kit can be stored, and the liquid reagent for the reaction is added to the peptide sample held in the sample container in a predetermined amount.
- a reaction container capable of holding a liquid reagent capable of maintaining a state in which they are not in direct contact with each other, and capable of storing the sample container therein, can evacuate the inside thereof and, after completion of the reaction, for the remaining reaction. It is preferable that the liquid reagent can be distilled off under reduced pressure, and the reaction can be carried out in an airtight structure.
- faucets used for sealing operation are preferably made of a material such as Teflon.
- the separation by a gel electrophoresis method is performed in advance in place of the dried sample of the peptide which has been subjected to the isolation treatment, which is the object of the first embodiment of the present invention.
- the present invention is directed to a peptide supported on the gel carrier. Therefore, for a peptide supported on a gel carrier, the reaction method in a solid phase that utilizes a vapor-like reaction reagent is effectively applied during the reaction to sequentially decompose the C-terminal amino acid. Since this is not possible, the method has been changed to infiltrate the corresponding reaction reagent into the gel carrier and perform a liquid phase reaction.
- the C-terminal amino acid is sequentially decomposed by chemical means from the target peptide corresponding to (1) to (3).
- the step of preparing a mixture containing a series of reaction products obtained by It enables a reaction to sequentially decompose the C-terminal amino acid on a peptide sample without being isolated from the gel carrier in advance and remaining on the gel carrier.
- Separation by gel electrophoresis is performed in advance, and it becomes an obstacle in the next pretreatment step of performing the acylation reaction on the target peptide sample supported on the gel carrier.
- To remove water in advance dilute and remove the aqueous solvent impregnated in the gel carrier using a polar aprotic solvent that does not cause the gel-like substance to dissolve and has an affinity for water.
- a step of performing a dehydration treatment of the gel carrier is provided, and a pretreatment step of performing the following acylation protection, a sequential decomposition step of the C-terminal amino acid, and a post-treatment step of performing a hydrolysis treatment of the reaction product are performed. .
- the gel substance used in the pre-separation by gel electrophoresis shows individual and separated spots (or bands) for multiple types of peptides corresponding to a specific molecular weight range.
- Conditions, specifically, the content ratio of polyacrylamide constituting the gel is selected, and the gap size of the fine hole structure formed inside the gel is adjusted.
- the separated spot (or band) for example, in the SDS-PAGE method, peptides having different electrophoretic velocities due to differences in peptide chain molecular weight and surface charge are respectively localized. .
- the peptide is held inside a fine pore structure formed in the gel, and does not cause the gel substance to dissolve when removing water impregnated in the gel substance, and If a method of diluting and eluting only a water solvent into the polar aprotic solvent using a polar aprotic solvent having an affinity for water is used, even after the completion of the dehydration operation, The retained peptide can be maintained on the gel carrier at the separated spot (or band) position.
- the polar aprotic solvent used in the above-mentioned dehydration treatment has an affinity for a gel-like substance such as polyacrylamide which constitutes the gel, which is generally inferior to an aqueous solvent.
- the bulk volume decreased.
- a polar aprotic solvent used in the dehydration treatment for example, when polyacrylamide gel is used, a suitable polar aprotic solvent such as acetonitrile (CH 3 CN), which has high affinity for water, is used. And -tolyls having 4 or less carbon atoms, and ketones having 4 or less carbon atoms such as acetone.
- the polar nonprotonic solvent used in these dehydration treatments evaporates more easily than water, and when evaporated and dried, its bulk volume is reduced and it becomes a contracted gel carrier.
- the pretreatment step of protecting the peptide chain with acylation comprises, after the dehydration treatment, a peptide sample to be supported on the gel carrier.
- the alkanoic anhydride can be infiltrated in the gel-like substance and maintained in a swollen state, in a dipolar aprotic solvent.
- the gel carrier is immersed in the alkanoic acid anhydride solution using a solution obtained by dissolving the alkanoic acid anhydride, thereby allowing the alkanoic acid anhydride to act on the peptide sample to be carried in the supported state.
- the amino group at the N-terminus of the peptide and the amino group on the side chain of the lysine residue that may be contained in the peptide have been previously derived from the alkanoic acid constituting the alkanoic anhydride.
- N-acylation protection by sil group Apply.
- the N-acylation protection for the amino group in the side chain of lysine residue, which is performed in this pretreatment step, is achieved by the above-mentioned final binding of the lysine residue to the C-terminal peptide bond when digested with triscine.
- the alkane by-produced remaining in the gel carrier is utilized. Since alkanoic acid can be used as a catalyst to promote the reaction, only alkanoic anhydride is used as the reaction reagent.
- the alkanoic anhydride used in this pretreatment step has an N-acylation protection reaction against the amino group of the side chain of lysine residue at a temperature selected in the range of 30 ° C to 80 ° C. It is preferable to use those exhibiting possible reactivity, specifically, symmetric acid anhydrides derived from alkanoic acids having 2 to 4 carbon atoms. In particular, it is more preferable to use a symmetrical anhydride derived from linear alkanoic acid having 2 to 4 carbon atoms. In other words, if a symmetrical alkanoic acid anhydride is used, the by-produced alkanoic acid is also of the same species.
- the molecular polarization of the alkanoic anhydride is induced and acts as an electrophilic reagent on the amino group of the peptide.
- the acylation reaction proceeds.
- a reaction temperature of 50 ° C or higher, but in general, such a reaction is carried out in a closed reaction vessel, so that the mechanical strength in the reaction vessel is reduced. Considering this, it is desirable to select the temperature within the range of 100 ° C. or less.
- Alkanic acid is produced along with the N-acylisani reaction, but in a small amount.
- the secondary reaction caused by the proton donating ability of such alkanoic acid and the coexisting alkanoic anhydride is not The above In the temperature range, this is usually not a problem. More specifically, the alkanoic acid generated in the system has, for example, a much lower acid catalysis and a smaller abundance than perfluoroalkanoic acid. Under the temperature condition, the main reaction in the step of sequentially decomposing the C-terminal amino acid using perfluoroalkanoic acid and arnic anhydride, until the secondary formation of the 5-oxazolone ring structure occurs. Does not reach.
- the above-mentioned dipolar aprotic solvent which causes the gel to re-swell can be infiltrated into the gel-like substance and can be maintained in a swelling state.
- Organic solvents with good affinity for the substance are preferred.
- the solvent is an excellent solvent.
- a dipolar aprotic solvent which is less likely to evaporate and evaporate is more preferable. For example, formamide (HCONH 2 ), etc. I am fully satisfied.
- the reaction is stopped by removing the alkanoic acid anhydride in the gel carrier, so that the gel-like substance is not dissolved, and alkanoic acid anhydride,
- the entire gel carrier is washed with a polar aprotic solvent having an affinity for a dipolar aprotic solvent. That is, by washing with the polar nonprotonic solvent, the arnic acid anhydride and the dipolar aprotic solvent that have infiltrated the gel carrier are diluted and removed by diffusion.
- a polar aprotic solvent that satisfies the requirements suitable for the above-mentioned washing application is, for example, an acetonitrile (CH 3 CN) or other carbon-containing solvent.
- CH 3 CN acetonitrile
- the polar aprotic solvent used in the dehydration treatment step described above as the polar aprotic solvent used for the dilution and washing.
- the polar aprotic solvent used in these washing treatments evaporates more easily than water, and when evaporated and dried, its bulk volume is reduced, resulting in a contracted gel carrier.
- the step of sequentially decomposing the C-terminal amino acid also usually takes a form in which the reaction reagent solution is infiltrated into the contracted gel carrier which does not contain water to start the reaction. Therefore, after pretreatment for N-acylation protection, the peptide is selected in the range of 30 ° C. to 80 ° C. with respect to the target peptide sample supported on the gel carrier. At temperature
- Perfluoroalkanoic acid is dissolved in a dipolar aprotic solvent that can infiltrate into the gel-like substance and can be maintained in a swollen state at a ratio that is small relative to arnic anhydride.
- R 1 represents the side chain of the C-terminal amino acid of the peptide
- R 2 represents a side chain of an amino acid residue located immediately before the C-terminal amino acid), and the C-terminal amino acid is sequentially decomposed with the cleavage of the 5-oxazolone ring. I do.
- the perfluoroalkanoic acid functions as a proton donor in the peptide chain carried in the hole of the gel carrier to increase the ratio of taking the enolole type. ing.
- the catalytic action of perfluoroalkanoic acid utilizes its proton donating ability, and the pKa of the perfluoroalkanoic acid is 0. It is preferred to use perfluoroalkanoic acids in the range of 3-2.5.
- the dipolar aprotic solvent used A perfluoroalkanoic acid having 2 to 4 carbon atoms, which can be uniformly dissolved therein, is more suitable, and a linear perfluoroalkanoic acid having 2 to 4 carbon atoms is more preferable.
- trifluoroacetic acid CF 3 COOH
- pentafluoropropanoic acid CF 3 CF 2 COOH
- heptafluorobutanoic acid CF 3 CF 2 CF 2 COOH
- the alkanoic anhydride used for activating the C-terminal carboxy group preferably gives an appropriate reactivity when the temperature is raised to the reaction temperature. Therefore, the symmetric type of alkanoic acid having 2 to 4 carbon atoms is preferable. It is preferable to use an acid anhydride. Of these, it is more preferable to use a symmetrical acid anhydride of a linear alkanoic acid having 2 to 4 carbon atoms as the symmetrical acid anhydride, and particularly to a symmetrical acid anhydride of a linear alkanoic acid having 2 carbon atoms. A type acid anhydride, that is, acetic anhydride can be suitably used.
- a strong alkanoic anhydride is preferably one that does not cause steric hindrance in its orientation in order to activate the C-terminal carboxy group and adopt a configuration suitable for forming a 5-year-old xazolone ring. In this regard, it is more preferable to use acetic anhydride.
- the alkanoic anhydride used as the above-mentioned activating reagent is consumed according to the reaction. Therefore, the alkanoic anhydride is used in advance in the reaction with the peptide in the dipolar aprotic solvent used for swelling of the gel. It is desirable to dissolve a large excess amount with respect to the consumed amount, and to suppress the concentration decrease.
- the content ratio of alkanoic anhydride to perfluoroalkanoic acid is 1 per 100 volumes of alkanoic anhydride and 1 perfluoroalkanoic acid.
- the content of the alkanoic anhydride in the dipolar aprotic solvent be selected in the range of 10 to 30% (vol%).
- the reaction time depends on the reaction temperature and the concentration of alkanoic anhydride and perfluoroalkanoic acid contained in the dipolar aprotic solvent.
- the dehydration treatment using a polar nonprotonic solvent Accordingly, it is desirable to appropriately select the gel carrier in consideration of the time required for swelling of the contracted gel carrier. For example, polyacrylamide-gel (12.5 mass./.) Is dehydrated using the above-mentioned acetonitrile, and then immersed in a dipolar aprotic solvent such as formamide described below.
- the time required to achieve re-swelling of the gel carrier is, for example, about 3 hours at 40 ° C. Therefore, the overall reaction time is such that after re-swelling of the gel carrier, the desired amino acid is obtained. Select the number of residues plus the time required to achieve selective degradation of the C-terminal amino acid.
- the above-mentioned dipolar aprotic solvent that causes the gel to re-swell can infiltrate into the gel-like substance and can be maintained in a swollen state, has a relatively small molecular size, and has a gel-like state.
- Organic solvents with good affinity for the substance are preferred.
- it shows a high dipolarity that can maintain the ratio of its enol form, and has a solute molecule of alkanoic anhydride, perfluoro. It is preferably an excellent solvent for alkanoic acid and alkanoic acid as a reaction by-product.
- a dipolar aprotic solvent which is less likely to evaporate and evaporate is more preferable.
- formamide (HCO NH 2 ) and the like are described above when a polyacrylamide gel is used. All requirements are fully satisfied.
- the dipolar non-protonic solvent that provides excellent solubility for the above-described alkanoic anhydride, perfluoroalkanoic acid, and arnic acid, which is a reaction by-product, is a water molecule. Can also be easily dissolved. Therefore, in the reaction treatment in the mixed solution using the dipolar aprotic solvent, the reaction system is preferably kept under a dry atmosphere from which water has been removed. That is, the reaction intermediate represented by the above formula (I b) is converted into an asymmetric acid anhydride, and the activated C-terminal carboxy group is hydrolyzed when water molecules are mixed into the reaction system. And return to the original terminal carboxy group. In order to avoid such an inactivation process, the reaction system is preferably maintained in a state where water is removed.
- the amino acid present in methionine may be oxidized by oxygen mixed into the system, and its formula amount may be changed.
- Preventing the oxidation by oxygen is more preferable in the method of the present invention based on the measurement of the molecular weight, in order to achieve higher accuracy in suppressing the oxidation.
- the reaction system is kept airtight to prevent moisture and oxygen from entering from outside the system.
- the liquid injection and discharge operations are also performed in a dried inert gas atmosphere, for example, a nitrogen atmosphere.
- a reaction represented by a reaction formula ( ⁇ ′) is obtained from a 5-oxazolone ring once formed, for example:
- Such a sequential C-terminal amino acid decomposition reaction is at least a process of forming a 5-oxazolone ring structure exemplified by the reaction formula (I b) and a cleavage of the 5-oxazolone ring structure exemplified by the reaction formula ( ⁇ ) And a two-step elementary reaction with the terminal amino acid separation process. Therefore, the overall reaction rate depends on both the reaction rate of each of these processes, but mainly depends on the reaction temperature if the concentration of the alkanoic anhydride and perfluoroalkanoic acid to be used is used.
- the processing time in the sequential step of selectively decomposing the C-terminal amino acid is mainly based on the alkanoic anhydride used and the perfluoroa. It is appropriately selected according to the concentration of lucanoic acid and the reaction temperature, and also considering the target amino acid length of the C-terminal amino acid sequence to be analyzed.
- the sequential termination of the selective decomposition reaction of the C-terminal amino acid lowers the temperature of the reaction system and reduces the reaction reagents infiltrating into the gel carrier, that is, perfluoroalnic acid and acetic anhydride.
- the mixed solution used for the sequential decomposition reaction of the C-terminal amino acid is used without causing the dissolution of the gel-like substance, and the perfluoroalkanoic acid and the alkanoic anhydride, and the dipolar
- the decomposition reaction is stopped and the reaction reagent is removed by diluting and removing using a polar aprotic solvent having affinity for the aprotic solvent.
- a dipolar non-protonic solvent used for preparing a mixed solution can be used, but the 5-oxazolone ring structure exemplified in the reaction formula (lb) can be used.
- a polar aprotic solvent that does not contribute much to stabilization of the phenolic intermediate is used. It is more desirable to use a removal step. At least in the final stage of the reaction reagent dilution / removal step, a dilution / removal operation using a polar aprotic solvent is provided.
- polar aprotic solvents satisfying these conditions include nitriles having 4 or less carbon atoms, such as acetonitrile (CH 3 CN), and carbon atoms, such as acetone. And 4 or less ketones.
- a series of reaction products obtained by a reaction for sequentially decomposing the C-terminal amino acid is subjected to a hydrolysis treatment.
- the post-treatment step also includes the step of preparing a peptide mixture containing these series of reaction products. This is carried out while being held on the gel carrier. That is, for a mixture containing a series of reaction products obtained by a reaction for sequentially decomposing the C-terminal amino acid, while being supported on the gel carrier,
- the reaction product peptide can be obtained in the presence of the basic nitrogen-containing organic compound.
- Water molecules act on the water to give water treatment.
- the basic nitrogen-containing aromatic ring compound or the tertiary amine compound is converted into a 5-year-old xazolone ring structure represented by the reaction formula ( ⁇ ′), and a reaction intermediate (acid anhydride) in the next stage.
- the basic nitrogen-containing aromatic ring compound or tertiary amine compound used for the above-mentioned hydrolysis treatment reacts, for example, with the remaining C-terminal having reached an asymmetric acid anhydride to form an amide bond. This is preferable because it does not form and can be made into a uniform solution when converted into an aqueous solution.
- a usable basic nitrogen-containing aromatic ring compound a monocyclic nitrogen-containing aromatic ring compound showing high solubility in a polar aprotic solvent is preferable, and for example, pyridine can be more suitably used.
- the tertiary amine compound that can be used preferably has a similar basicity to the relatively weak basicity of the pyridine base.
- DMAE ((CH 3 ) 2 N-CH 2 CH 2 2 OH)
- pyridine when pyridine is used, it is preferable to select pyridine in the range of 5 to 15% by volume, more specifically, 10% by volume, based on the total volume of the aqueous solution.
- DMAE dimethylamino ethanol
- DMAE should be selected in the range of 1 to 20% by volume, more specifically, 10% by volume, based on the total volume of the aqueous solution. Preferred Les ,.
- the main purpose of the hydrolysis using an aqueous solution containing an organic base is to expose a carboxy group at the C-terminus of the peptide chain of the reaction product.
- the deprotection of the acylation protection proceeds at the same time, while the N-acylation protection for the amino group at the N-terminal and the amino group on the side chain of the lysine residue is selected so that the deprotection does not proceed. ing.
- the nitrogen base forms an addition salt with respect to the carboxy group at the C-terminal of the reaction product.
- the aqueous solution impregnated in the gel carrier is diluted with a polar aprotic solvent that does not cause dissolution of the gel substance and has compatibility with water. It is preferable that the gel carrier is subjected to a re-dehydration treatment by removing, and a basic nitrogen-containing aromatic ring compound or a tertiary amine compound used for the hydrolysis treatment is diluted and removed together with water. Therefore, the polar aprotic solvent used in this re-dehydration step is preferably one having high solubility also for a basic nitrogen-containing aromatic ring compound or a tertiary amine compound.
- polar aprotic solvents for the redehydration step that satisfy these conditions include nitriles having 4 or less carbon atoms such as acetonitrile (CH 3 CN). Examples thereof include ketones having 4 or less carbon atoms, such as acetone.
- the above-mentioned hydrolysis treatment after the sequential decomposition reaction of the C-terminal amino acid, is carried out once to polar alkanoic acid and perfluoroalkanoic acid of the reaction reagent. Not only after completion of the dilution / removal operation using an aprotic solvent, but also the sequential decomposition reaction of the C-terminal amino acid and the hydrolysis treatment can be performed continuously. Specifically, the sequential decomposition reaction of the C-terminal amino acid is performed by lowering the reaction temperature and stopping the reaction while adding an aqueous solution containing an organic base to obtain an alkanoic anhydride and a perfluoroalkanoic acid.
- reaction reagents and elution from the gel occur in combination with the combination of the above, stopping the sequential decomposition reaction of the C-terminal amino acid and inactivating and removing the reaction reagents.
- the reaction product can be subjected to a hydrolysis treatment, and finally, a re-dehydration treatment step using a polar aprotic solvent can be performed to cope with the alkanoic anhydride together with the aqueous solution containing the organic base. Removal of the alkanoic acid, perfluoroalkanoic acid, and the dipolar nonprotonic solvent and re-dehydration are performed. However, there is no substantial difference.
- the trypsin digestion treatment is carried out to obtain the amino acid.
- a MA LDI-TOF-MS method measure the molecular weight of the dried mixture containing the tryptic digested peptide fragment obtained by fragmenting the long peptide chain and using the cation species generated in the ionization treatment. , And a molecular weight measurement using anion species.
- one of the features of the second embodiment of the present invention is that the mixture containing the series of reaction products that have been subjected to the hydrolysis treatment is subjected to re-dehydration treatment and then supported on the gel carrier.
- the step of such a trypsin digestion treatment is performed. Specifically, after the re-dehydration treatment, the mixture containing the series of reaction products having been subjected to the hydrolysis treatment is reacted with trypsin dissolved in a buffer solution while being supported on the gel carrier.
- a trypsin enzyme of the peptide chain wherein the N-acylation protection for the amino group at the N-terminal of the peptide chain and the amino group of the side chain of a lysine residue that may be contained in the peptide chain is maintained.
- Specific digestion treatment is performed to perform peptide fragmentation by selective cleavage of the C-terminal peptide bond of the arginine residue present in the peptide chain.
- gel carriers used for molecular weight separation by gel electrophoresis such as two-dimensional electrophoresis and SDS-PAGE, hold peptide chains having an amino acid length exceeding a certain range in the pore structure in the gel.
- the specificity of the gel carrier used for the gel electrophoresis is utilized to maintain the long amino acid-length peptide chain while maintaining the state supported on the gel carrier. After sequentially decomposing and removing the C-terminal amino acids and preparing a series of reaction products, the peptide is fragmented by trypsin digestion to obtain a target group of C-terminal peptide fragments. However, it can be easily eluted from the gel carrier and recovered.
- the peptide chain when performing this trypsin digestion treatment, in the case of the mixture containing the series of reaction products after the hydrolysis treatment, if the N-terminal amino group of the peptide chain is ⁇ , the peptide chain is Cleavage of the C-terminal peptide bond of the N-acylated protected lysine residue since the N-acylated protection for the amino group of the lysine residue side chain that may be contained in Does not occur, and selective cleavage of the C-terminal peptide bond of the arginine residue present in the peptide chain occurs.
- the target group of C-terminal peptide fragments is usually a few amino acids in length of the original peptide chain, and thus is released from the gel carrier and eluted into the trypsin solution.
- the other peptide fragments are also eluted in the same manner.
- the buffer solution and the gel carrier are separated, the released various peptide fragments are recovered in the buffer solution. Thereafter, a desalting treatment is performed to remove the buffer solution component, and the tryptic digested peptide fragment is recovered and dried.
- the subsequent steps that is, the recovered dry mixture containing the tryptic digested peptide fragment was analyzed using the MA LDI-TOF-MS method.
- the operations up to the measurement of the child amount and the determination of the C-terminal amino acid sequence based on the measurement result are the same as those in the above-described first embodiment of the present invention.
- the method for analyzing the C-terminal amino acid sequence of a peptide according to the second embodiment of the present invention is based on gel electrophoresis such as two-dimensional electrophoresis or s DS-PAGE from a sample containing various proteins.
- the approximate molecular weight of the protein separated by the method can be estimated, and even if the protein is isolated and recovered from the separated spot (or band), the number of amino acids is large.
- a group of C-terminal peptide fragments is used, and then the molecular weight is measured and the C-terminal amino acid sequence is determined based on the measurement results.
- the separated spots can be used instead of isolating and recovering such proteins from separated spots (or bands).
- Cut out of the gel carrier while holding onto the gel carrier, and performs a series of chemical treatments. It is possible to omit the step of isolating and recovering the protein in the form of a spot (or band) that has been separated in advance, and to achieve the same accuracy without being affected by the recovery yield in the isolation and recovery step. It is possible to carry out the determination of the C-terminal amino acid sequence.
- the peptide sample of interest is a linear peptide, which is separated by gel electrophoresis in advance, and is loaded on the gel carrier.
- the gel electrophoresis method is not limited to the conventional SDS-PAGE method in which electrophoresis is performed in a one-dimensional direction. Alternatively, those to which the two-dimensional electrophoresis method is applied may be used.
- the peptide sample separated by the method according to the second aspect of the present invention can be used even in a small sample amount without contamination by contaminants. Amino acid sequencing is now possible.
- FIG. 1 shows a process flow of the step of sequentially decomposing C-terminal amino acids in Example 1.
- a peptide solution containing only a globin-peptide chain portion at a concentration of 1. O ⁇ ug Z ⁇ uL is prepared from a commercially available pima 'myoglobin sample. The peptide solution is placed in a test tube and freeze-dried to prepare a dry peptide powder sample.
- the pial containing the dried peptide sample was placed in a Teflon cock bar. Attach it in a glass-made reaction vessel of a stoppered airtight test tube type equipped with a port for vacuum evacuation that is sealed with a lube, and separately put a predetermined amount of the following liquid reagent into this glass-made reaction vessel.
- a pretreatment reagent acetic anhydride (300 ⁇ L) to which 5% by volume of acetic acid was added was used.
- the vial containing the dried peptide sample was placed in the glass reaction vessel, and then the reaction vessel was cooled.
- the inside of the reaction vessel is kept at 50 ° C for 2 hours, and acetic anhydride and acetic acid in vapor form are supplied from the liquid reagent in the vessel.
- acetic anhydride and acetic acid in vapor form are supplied from the liquid reagent in the vessel.
- N-acetylation of the lysine residue (1-NH—CH (CH 2 CH 2 CH 2 CH 2 NH 2 ) -CO-) to the ⁇ -position amino group contained in the peptide chain is performed.
- the obtained vial holding the globin / peptide chain modified / protected by the acetyl group was placed in a glass reaction vessel of the same type with a stoppered airtight test tube. A predetermined amount of the following liquid reagent is separately placed in the reaction vessel.
- Heputafuruoro butanoic acid As liquid reagent for the selective decomposition of the C-terminal amino acids, Heputafuruoro butanoic acid (HFBA: C 3 F 7 CO_ ⁇ _H) the use of a 1 volume 0/0 added acetic anhydride (300 L), the glass reaction After storing the vial containing the dried sample in the container, the reaction container is evacuated under cooling and sealed in an airtight state under cooling.
- the entire airtight reaction vessel is kept at 40 ° C for 3 hours, and the liquid sample in the vessel is Vaporous acetic anhydride and HFBA from the drug are applied to the dried peptide sample.
- the HFBA and acetic anhydride act on the C-terminal of the peptide chain at the above-mentioned heating temperature, and through the above-mentioned reaction formulas (Ia) to ( ⁇ ′), A sequential decomposition reaction of the terminal amino acid proceeds.
- the C-terminus of the peptide chain of the strong reaction product is in the form of an asymmetric acid anhydride in which the 5-oxazolone ring or the carbonyl group described above has been activated.
- the vial holding the dried sample of the mixture containing the reaction product also attached in a glass reaction vessel of the airtight test tube type with a stopper the glass A predetermined amount of the liquid reagent to be added is added.
- This post-treatment is mainly carried out in the above-mentioned mixture, in which the C-terminal of the reaction product peptide is not converted to a hydroxyl group, but remains in a 5-oxazoline structure, or is an asymmetric acid anhydride. Since the product that has progressed to the conversion into a product is also in the form of a contained mixture, it is subjected to a hydrolysis treatment to convert the C-terminus of the peptide into a carboxy group.
- the whole hermetically sealed reaction vessel is heated at 60 ° C for 1 hour, and the vapor DMAE and water molecules supplied from the liquid reagent in the vessel are allowed to act on the dried sample.
- the asymmetric acid anhydride and the 5-oxazolone structure are hydrolyzed by the action of a water molecule in the presence of the organic base, DMAE, as shown in the above reaction formula (IV). It is converted into a form having a carboxy group at the terminal.
- globin-peptide chain of myoglobin is composed of 153 amino acids, it deviates from the appropriate molecular weight range in mass spectrometry, and peptide fragmentation by trypsin digestion is performed.
- a sample obtained by drying the mixture of the post-treated reaction product is placed in a container, an aqueous solution containing trypsin is added, and fragmentation of the peptide chain is performed.
- the aqueous solution containing trypsin contains trypsin at a concentration of 0.1 ⁇ g / ⁇ L in a 3-pyridine acetate buffer (pH 7), and trypsin digestion is performed at 37 ° C. with stirring. And perform the enzyme reaction for 8 hours.
- the original peptide chain and the reaction product are also subjected to N-acetylation of the N-terminal amino group and lysine residue (one NH—CH (CH 2 CH 2 CH 2 The N-acetylation of the CH 2 NH 2 ) -CO-) to the amino group at the ⁇ -position is maintained. No cleavage occurs, and only cleavage of the C-terminal peptide bond of the arginine residue proceeds. This poma. Globin of myoglobin The amino acid sequence of the tide chain has already been determined. Fragments containing the partial amino acid sequences of 2-139 and 140-153 are generated.
- reaction solution is subjected to desalting treatment using Zip Tip, separation and recovery of peptide fragments, and then lyophilization of these peptide fragments.
- reaction product after peptide fragmentation by post-treatment and trypsin digestion Reaction product after post-treatment and peptide fragmentation and C-terminal fragment of globin 'peptide chain obtained by performing the above series of treatments
- molecular weight of each contained peptide fragment is measured by mass spectrometry.
- the mass of the main ion species reflecting the molecular weight of each peptide fragment and the relative signal intensity were measured using a MA LDI-TOF-MS device on the dried peptide fragment mixture sample. Perform measurement and comparison.
- the separation of ion species is performed by measuring the so-called negative mode, in which a negatively charged ion species is guided to a detector, and detecting the positively charged ion species by a detector. To the so-called positive mode measurement.
- the peak having a relatively large intensity was determined to correspond to the C-terminal peptide fragment of the 140-153 partial amino acid sequence that did not contain an arginine residue.
- a peptide fragment corresponding to the partial amino acid sequence of 78-102 derived from cleavage at the lysine residue from which the N-acetylino group was removed in the partial amino acid sequence of 32-139 was also found.
- the intensity shows a relatively large peak.
- peptide fragments generated by autolysis of trypsin are also found in such a molecular weight range.
- the intensity shows a relatively large peak.
- the ionic species corresponding to the peptide fragment having a lysine residue at the C-terminus, which has lost acetylation protection, can be easily identified.
- tryptic digested peptide fragments of lysine residues can be used in such a range of molecular weights. Therefore, the task becomes easier when discriminating between a target C-terminal peptide fragment and a series of C-terminal peptide fragments in which the accompanying C-terminal amino acid is sequentially degraded.
- poma myoglobin which is a sample to be analyzed, was subjected to gel electrophoresis by SDS-PAGE using polyacrylamide gel, and the globin peptide chain was separated as a single spot. After that, the identification accuracy of the C-terminal amino acid sequence identified by the analysis method according to the present invention was verified.
- a reducing agent such as H: 2-mercaptoethanol
- DTT dithiothreitol: threo-1,4-disulfanil-2,3-butanediol
- the sulfanyl group (1-SH) of the cysteine residue is protected by carboxymethylation or the like in advance.
- the peptide solution gel concentration 1 2. spots to 5 mass 0/0 of polyacrylamide de on the gel after electrophoresis treatment, 'staining, globin an object' Coomassie specific bands peptide chain I do.
- the gel in the staining band is cut out and the gel slice is subjected to the following series of operations.
- the gel slice is placed in an airtight tube, and 1 mL of acetonitrile is injected, followed by stirring for 15 minutes. Thereafter, the acetonitrile is discarded, and 1 ml of acetonitrile is newly added, and the mixture is further stirred for 15 minutes. Extraction of water impregnated in the gel using this acetonitrile is performed three times in total, and the gel is dehydrated. The gel volume shrinks during the dehydration treatment.
- N-acetylation of the lysine residue (one NH—CH (CH 2 CH 2 CH 2 CH 2 NH 2 ) —CO—) to the ⁇ -position amino group contained in the peptide chain, , O-acetylation of a hydroxy group present in a serine residue (—NH—CH (CH 2 OH) —CO—) or a threonine residue (one NH—CH (CH (CH 3 ) OH) —CO—), O-acetylation of a tyrosine residue (one NH—CH (CH 2 —C 6 H 4 —OH) —CO—) to a phenolic hydroxy group is performed.
- the formamide solution of acetic anhydride is removed, and the mixture is placed in a tube container. Inject 1 mL of acetonitrile and stir for 15 minutes. Thereafter, the acetonitrile is discarded, 1 ml of acetonitrile is newly added, and the mixture is further stirred for 15 minutes. Extraction of the formamide solution impregnated in the gel using this acetonitrile is performed three times in total, and the solvent removal (formamide) treatment in the re-swelled gel is performed. With the desolvation treatment, the gel volume shrinks, and at the same time, the gel is dehydrated.
- the gel shrunk by the dehydration treatment is re-swelled and the reaction reagent is infiltrated into the gel. Specifically, after completion of the pretreatment operation, the obtained globin modified with an acetyl group is protected.
- Furuorobutan acid (HFBA: C 3 F 7 COOH ) 1 volume 0/0, injecting the formamide solution 1 mL of acetic anhydride 10 volume 0/0.
- HFBA C 3 F 7 COOH
- the gel that initially shrinks in volume re-swells and returns to its original volume as the solvent infiltrates formamide.
- HFBA and acetic anhydride were heated at the heating temperature to the C-terminal of the peptide chain supported in the re-swelled gel.
- the selective degradation of the C-terminal amino acid of the peptide chain proceeds.
- the sequential decomposition reaction of the amino acid at the C-terminal of the peptide chain via the 5-oxazolone ring formation via the reaction pathways of the above-mentioned reaction formulas (Ia) to ( ⁇ ) Is estimated to progress.
- Each of the successive decomposition processes is promoted by the catalytic action of HFBA functioning as a proton donor in formamide, a dipolar solvent.
- the sequential decomposition reaction of the C-terminal amino acid proceeds, and the gel remains at the point of conversion to a series of reaction products from which the C-terminal amino acid has been gradually removed and to the first-stage 5-oxazolone structure However, the mixture containing the original peptide chain modified and protected by the acetyl group remains in a state of being supported on the gel carrier.
- the unreacted formamide solution containing unreacted anhydrous acetic acid and HFBA remaining in the container is removed, and acetonitrile lmL is injected into the container. Stir for a minute.
- the mixture containing the reaction product was put gel slice of the condition being carried in the container, DMA E ((CH 3) 2 N- CH 2 CH 2 ⁇ _H) 1 0 vol 0/0 concentration Inject 1 mL of aqueous solution.
- DMA E ((CH 3) 2 N- CH 2 CH 2 ⁇ _H) 1 0 vol 0/0 concentration
- Inject 1 mL of aqueous solution While stirring the stoppered container, the temperature of the entire container is heated to 60 ° C. and maintained at such temperature for 1 hour. At this time, the gel that has been dehydrated rapidly re-swells and returns to its original volume as the solvent water infiltrates.
- the water treatment proceeds.
- the hydrolysis treatment in this post-treatment is mainly based on the fact that, in the above mixture, the C-terminal of the reaction product peptide has a 5-oxazolone structure other than that converted into a carboxy group. Those that remained in the mixture or those that had progressed to conversion to the asymmetric acid anhydride were in the form of a mixed mixture.
- the C-terminus is a process for converting to a carboxy group.
- a serine residue one NH—CH (CH 2 OH) —CO 2 -
- Ya threonine residue an NH- CH (CH (CH 3) OH) -CO-
- deprotection is performed.
- Hydrolysis of O-acetylation protection of tyrosine residues one NH—CH (CH 2 —C 6 H 4 —OH) —CO—
- phenolic hydroxy groups proceeds in a similar manner.
- the aqueous solution remaining in the container is removed, 1 mL of acetonitrile is poured into the container, and the mixture is stirred for 15 minutes. Thereafter, the acetonitrile is discarded, and acetonitrile lnxL is newly injected, followed by further stirring for 15 minutes. Extraction of the aqueous solution impregnated in the gel using this acetonitrile is performed three times in total, and dehydration treatment in the re-swelled gel is performed. Gel volume shrinks during dehydration.
- the globin 'peptide chain of myoglobin is composed of 153 amino acids, it deviates from the appropriate molecular weight range in mass spectrometry, and peptide fragmentation by trypsin digestion is performed.
- a trypsin-containing aqueous solution is added to the container in which the post-treated and dehydrated gel slices are placed, and the gel is supported on the gel carrier. Perform fragmentation of the peptide chain.
- the trypsin-containing aqueous solution contains trypsin at a concentration of 0.067 g / ⁇ L in ammonium bicarbonate buffer (pH 8), and the trypsin digest is stirred at 37 ° C. Perform the enzyme reaction for 4 hours. At that time, the gel that has been dehydrated quickly re-performs as the solvent water infiltrates, and returns to its original volume. By reacting the peptide chains and reaction products carried in the re-swelled gel with trypsin infiltrating into the gel together with the buffer at the heating temperature, the enzyme digestion specific to trypsin is performed. Progresses.
- the peptide chain and the reaction product are also deprotected in the above-mentioned post-treatment step, N-acetylation of the N-terminal amino group, lysine residue (one NH—CH (CH 2 CH 2 CH 2 CH 2 NH 2 ) N-acetylation of the amino group at the E-position of -CO-) is maintained, and cleavage of the C-terminal peptide bond of the N-acetylated lysine residue is not performed by trypsin digestion. The cleavage of the C-terminal peptide bond of the arginine residue proceeds.
- the amino acid sequence possessed by the globin-peptide chain of this pima 'myoglobin has already been determined, and as shown in FIG.
- the peptide chain undergoes trypsin digestion into fragments containing each of the partial amino acid sequences of 131, 32-139, and 140-153.
- lysine residues protected by N-acetylation during pretreatment are shaded, and tryptic digestion results in cleavage of the C-terminal peptide bond of arginine residues.
- the resulting partial amino acid sequences of the N-terminal 1 31 1 and the C-terminal 140-153 are shown in bold.
- the fragmented peptide eluted into the trypsin solution in the container is recovered from the gel. After desalting the solution containing the recovered mixture of peptide fragments, vacuum drying is performed.
- reaction product after peptide fragmentation by post-processing and trypsin digestion Reaction product after post-processing and peptide fragmentation and C-terminal fragment of globin / peptide chain obtained by performing the above series of treatments
- molecular weight of each contained peptide fragment is measured by mass spectrometry.
- a main ion reflecting the molecular weight of each peptide fragment was applied to the peptide fragment mixture sample that had been desalted and dried. Measure and compare the mass of the species peak and its relative signal strength.
- the separation of ion species is performed by leading a negatively charged ion species to a detector, so-called “negative 'mode measurement, and leading a positively charged ion species to a detector. Both so-called positive mode measurements are performed.
- a peptide fragment corresponding to the partial amino acid sequence of 78-102 which is derived by cleavage at the lysine residue from which the N-acetyl group has been removed in the partial amino acid sequence of 32-139.
- the intensity shows a relatively large peak.
- peptide fragments produced by autolysis of trypsin are also found in this molecular weight range, and similarly, in the positive mode measurement shown in FIG. 5, the intensity shows a relatively large peak.
- the two amino acids from the C-terminal, glycine and glutamine are sequentially degraded by the C-terminal amino acid.
- a peak derived from the reaction product that is sequentially decomposed is confirmed.
- the peptide chain separated as a band on the above-mentioned gel slice to be analyzed is actually a globin / peptide chain, and a state in which the C-terminal amino acid sequential degradation treatment is carried on the gel.
- the N-terminal amino acid sequence obtained by digesting the peptide chain with trypsin while protecting the lysine residue side chain with N-acylation is used.
- the common peptide fragment derived therefrom is used as a peptide fragment having an arginine residue at the C-terminus, and is used to distinguish it from the C-terminal peptide fragment. Even if the peptide chain to be analyzed originally has arginine at the C-terminus, it is important to reflect the molecular weight of each peptide fragment in the measurement using the MALD I-TOF-MS instrument.
- a vial holding a dried sample of the above-mentioned peptide sample (Ac-EGVN DNEEGFFSAR) obtained by N-acetylation treatment in advance is attached to an airtight test tube type glass reaction vessel with a stopper.
- a predetermined amount of the following liquid reagent is separately charged into the glass reaction vessel.
- a liquid reagent for the selective decomposition reaction of the C-terminal amino acid 5 volumes of trifluoroacetic acid were used. / 0 using the added acetic anhydride (300 L), after storing vial housing the dry sample into the glass reaction vessel, under cooling, the reaction vessel was vapor vacuum exhaust is sealed airtight. The entire hermetically sealed reaction vessel is kept at 40 ° C. for 16 hours, and vaporized acetic anhydride and trifluoroacetic acid supplied from the liquid reagent in the vessel are allowed to act on the dried sample.
- the entire hermetically sealed reaction vessel is heated at 100 ° C. for 30 minutes, and vapor pyridine and water molecules supplied from the liquid reagent in the vessel are allowed to act on the dried sample.
- the O-acetylation protection of the serine residue is deprotected, but the hydrolysis of the N-terminal N-acetylation protection of the amide bond does not occur.
- an N-acetylated compound in which the acetyl group is modified at the N-terminal of the peptide is obtained.
- the positive mode is a positive ion to which a proton (H +) is added
- the negative ion mode is a positive ion to which a proton (H + ) is released.
- the original peptide fragment that retains the amino acid sequence of 1 to 14 has a relatively large intensity and arginine. It is confirmed that it contains a residue.
- a peak corresponding to the molecular weight from which the arginine residue was decomposed and removed from the original peptide fragment was observed, while in the positive mode measurement, a corresponding peak was observed. The peak is not clearly found.
- the original peptide fragment that retains the amino acid sequence of 11-14 has an arginine residue at the C-terminus, and in the positive mode measurement, the intensity is relatively large, but the negative mode
- an ion species originating from a series of accompanying reaction products was found, and a peak corresponding to the molecular weight from which arginine residues were decomposed and removed was present. Is confirmed to have been received.
- Table 3 shows the measured mass of the peak, the difference from the mass of the peak due to the original peptide chain, and the amino acids removed from each reaction product fragment identified therefrom. Shows the form of the reaction product.
- the method for analyzing the C-terminal amino acid sequence of a peptide comprises the steps of: (a) sequentially decomposing and removing the C-terminal amino acid of the peptide; Amino groups, as well as for Amino groups of lysine residue side chain, N- Ashiru of protection by performing, at the same time, a serine residue (an NH- CH (CH 2 0 H) - CO -) Ya threonine residue even for hydroxy groups present in the group (one NH- CH (CH (CH 3) OH) -CO I), in a state in which O- Ashiru of protection is made a dry atmosphere, in mild heating temperature, alkanes A reaction reagent obtained by combining a small amount of perfluoroalkanoic acid with an acid anhydride is allowed to act.
- the alkanoic anhydride used itself has low reactivity, so that unnecessary side reactions such as cleavage of an amide bond in the middle of the peptide do not occur, and the C-terminal amino acid of the peptide can be obtained under mild heating conditions. Can be sequentially decomposed and removed. Concomitantly, there is no fragmentation of the amide bond in the middle of the peptide. Mixing can also be avoided. Further, by utilizing the reaction under such mild conditions, a series of reaction products obtained is subjected to post-treatment in the presence of an organic basic compound by hydrolyzing, so that a carboxy terminal is obtained at the C-terminal.
- the shortened C-terminal amino acid sequence can be determined with high accuracy.
- the amino acid length change of the peptide chain is at most about 10 amino acids.
- these chemical treatments can be advanced while maintaining the state of being supported on the gel carrier.
- tryptic digestion and peptide fragmentation are performed, peptide fragments with a significantly shorter amino acid length can no longer be stably retained on the gel carrier, and can be easily eluted and recovered from the gel carrier. It becomes.
- the method for analyzing the C-terminal amino acid sequence of peptides according to the present invention is a more versatile analysis method. It becomes.
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AU2003289172A AU2003289172A1 (en) | 2002-12-10 | 2003-12-04 | Method of analyzing c-terminal amino acid sequence of peptide |
US10/538,305 US7651859B2 (en) | 2002-12-10 | 2003-12-04 | Method of analyzing c-terminal amino acid sequence of peptide |
EP03777240A EP1582872A4 (en) | 2002-12-10 | 2003-12-04 | METHOD FOR ANALYZING A C-TERMINAL AMINO ACID SEQUENCE OF A PEPTIDE |
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JP2002357972A JP4086642B2 (ja) | 2002-12-10 | 2002-12-10 | ペプチドのc末端アミノ酸配列解析方法 |
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US20110053196A1 (en) * | 2006-02-08 | 2011-03-03 | Nec Corporation | Method for modifying a peptide and a method for identifying a peptide |
EP1983346A4 (en) * | 2006-02-08 | 2010-03-17 | Nec Corp | METHOD FOR CLEAVING A PEPTIDE BOND AT THE C-TERMINAL END OF A PEPTIDE, AND A METHOD FOR DETERMINING THE C-TERMINAL END-ACE AMINO ACID SEQUENCE OF A PEPTIDE |
Citations (5)
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JPH0627113A (ja) * | 1992-07-08 | 1994-02-04 | Seiko Instr Inc | タンパク質あるいはペプチドのカルボキシ末端からのアミノ酸配列を決定する方法 |
JPH10293130A (ja) * | 1996-05-24 | 1998-11-04 | Seiko Instr Inc | タンパク質あるいはペプチドのカルボキシ末端からのアミノ酸配列を決定する方法 |
JP2000146983A (ja) * | 1990-08-13 | 2000-05-26 | City Of Hope | ペプチド及び蛋白質の連続c末端分解 |
JP2002189029A (ja) * | 2000-12-21 | 2002-07-05 | Sumitomo Chem Co Ltd | タンパク質のn末端のアミノ酸配列決定方法 |
JP2003279581A (ja) * | 2002-03-25 | 2003-10-02 | Nec Corp | ペプチドのc末端アミノ酸配列解析方法 |
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CA1340966C (en) * | 1989-05-19 | 2000-04-18 | Thomas R. Covey | Method of protein analysis |
JP2686506B2 (ja) | 1991-11-15 | 1997-12-08 | セイコーインスツルメンツ株式会社 | タンパク質あるいはペプチドのカルボキシ末端からのアミノ酸配列を決定する方法 |
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- 2003-12-04 US US10/538,305 patent/US7651859B2/en not_active Expired - Fee Related
- 2003-12-04 AU AU2003289172A patent/AU2003289172A1/en not_active Abandoned
- 2003-12-04 WO PCT/JP2003/015522 patent/WO2004053498A1/ja active Application Filing
- 2003-12-04 EP EP03777240A patent/EP1582872A4/en not_active Withdrawn
Patent Citations (5)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
JP2000146983A (ja) * | 1990-08-13 | 2000-05-26 | City Of Hope | ペプチド及び蛋白質の連続c末端分解 |
JPH0627113A (ja) * | 1992-07-08 | 1994-02-04 | Seiko Instr Inc | タンパク質あるいはペプチドのカルボキシ末端からのアミノ酸配列を決定する方法 |
JPH10293130A (ja) * | 1996-05-24 | 1998-11-04 | Seiko Instr Inc | タンパク質あるいはペプチドのカルボキシ末端からのアミノ酸配列を決定する方法 |
JP2002189029A (ja) * | 2000-12-21 | 2002-07-05 | Sumitomo Chem Co Ltd | タンパク質のn末端のアミノ酸配列決定方法 |
JP2003279581A (ja) * | 2002-03-25 | 2003-10-02 | Nec Corp | ペプチドのc末端アミノ酸配列解析方法 |
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AU2003289172A8 (en) | 2004-06-30 |
EP1582872A1 (en) | 2005-10-05 |
EP1582872A4 (en) | 2008-08-13 |
US7651859B2 (en) | 2010-01-26 |
US20060057731A1 (en) | 2006-03-16 |
JP2004191123A (ja) | 2004-07-08 |
AU2003289172A1 (en) | 2004-06-30 |
JP4086642B2 (ja) | 2008-05-14 |
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