WO2017170469A1 - アミノ酸定量方法及びアミノ酸定量用キット - Google Patents
アミノ酸定量方法及びアミノ酸定量用キット Download PDFInfo
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- WO2017170469A1 WO2017170469A1 PCT/JP2017/012511 JP2017012511W WO2017170469A1 WO 2017170469 A1 WO2017170469 A1 WO 2017170469A1 JP 2017012511 W JP2017012511 W JP 2017012511W WO 2017170469 A1 WO2017170469 A1 WO 2017170469A1
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- C—CHEMISTRY; METALLURGY
- C12—BIOCHEMISTRY; BEER; SPIRITS; WINE; VINEGAR; MICROBIOLOGY; ENZYMOLOGY; MUTATION OR GENETIC ENGINEERING
- C12Q—MEASURING OR TESTING PROCESSES INVOLVING ENZYMES, NUCLEIC ACIDS OR MICROORGANISMS; COMPOSITIONS OR TEST PAPERS THEREFOR; PROCESSES OF PREPARING SUCH COMPOSITIONS; CONDITION-RESPONSIVE CONTROL IN MICROBIOLOGICAL OR ENZYMOLOGICAL PROCESSES
- C12Q1/00—Measuring or testing processes involving enzymes, nucleic acids or microorganisms; Compositions therefor; Processes of preparing such compositions
- C12Q1/25—Measuring or testing processes involving enzymes, nucleic acids or microorganisms; Compositions therefor; Processes of preparing such compositions involving enzymes not classifiable in groups C12Q1/26 - C12Q1/66
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- G—PHYSICS
- G01—MEASURING; TESTING
- G01N—INVESTIGATING OR ANALYSING MATERIALS BY DETERMINING THEIR CHEMICAL OR PHYSICAL PROPERTIES
- G01N27/00—Investigating or analysing materials by the use of electric, electrochemical, or magnetic means
- G01N27/26—Investigating or analysing materials by the use of electric, electrochemical, or magnetic means by investigating electrochemical variables; by using electrolysis or electrophoresis
- G01N27/403—Cells and electrode assemblies
- G01N27/414—Ion-sensitive or chemical field-effect transistors, i.e. ISFETS or CHEMFETS
- G01N27/4145—Ion-sensitive or chemical field-effect transistors, i.e. ISFETS or CHEMFETS specially adapted for biomolecules, e.g. gate electrode with immobilised receptors
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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
- G01N33/6806—Determination of free amino acids
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- G—PHYSICS
- G01—MEASURING; TESTING
- G01N—INVESTIGATING OR ANALYSING MATERIALS BY DETERMINING THEIR CHEMICAL OR PHYSICAL PROPERTIES
- G01N2333/00—Assays involving biological materials from specific organisms or of a specific nature
- G01N2333/90—Enzymes; Proenzymes
- G01N2333/9015—Ligases (6)
Definitions
- the present invention relates to an amino acid quantification method, an amino acid quantification kit, and the like.
- L-amino acid plays an important role as a component of protein in living body, and there are 20 kinds thereof.
- free L-amino acids in food are related to taste, aroma after heating, storage stability, bioregulatory function after ingestion, etc., and are attracting attention as important factors in the fields of food science and nutrition science.
- the L-amino acid concentration in the blood changes due to disease, and by measuring the amino acid concentration in the blood, a biomarker that enables cancer diagnosis such as lung cancer, stomach cancer and colon cancer It is also used as.
- D-amino acids As amino acids, there are D-amino acids (D-AA), which are optical isomers of L-amino acids, and there are 19 types. Although D-amino acids exist in the living body, their physiological functions have not been clearly understood. However, in recent years, with the development of analytical techniques, D-amino acids can be analyzed. For example, D-serine is increased in the cerebrospinal cord of Alzheimer's patients, and D-aspartic acid decreases with skin aging. It has been found that D-alanine is involved in the sweetness of crabs and shrimps, and the physiological functions of D-amino acids have attracted attention. Therefore, amino acid quantification techniques for L-form and D-form are indispensable techniques in various fields such as product development using amino acids, quality control, and diagnosis.
- an amino acid quantification technique for L-amino acids a method is known in which amino acids are separated by liquid chromatography and detected by a color reaction using ninhydrin or a fluorescent derivatizing agent orthophthalaldehyde.
- D-amino acid quantification technique D-amino acid is diastereomer fluorescence-induced by adding a fluorescent derivatizing agent orthophthalaldehyde and a chiral derivatizing agent Nacyl-L-cysteine, and analyzed by liquid chromatography.
- a stereomer method and a two-dimensional liquid chromatography method are known (Non-Patent Document 1).
- this method has a problem that it takes about 2 hours to analyze one sample, so that it takes a long time for analysis and is not suitable for measuring a large number of samples.
- Patent Document 1 an amino acid measurement method using an enzyme that acts on L-amino acids or D-amino acids is known (Patent Document 1, Non-Patent Document 1).
- this method has a low selectivity for the target amino acid, reacts with amino acids other than the target, and there are no enzymes corresponding to 20 types of amino acids (19 types in the case of D-amino acids). was there.
- AARS aminoacyl tRNA synthetase
- L-AA L-amino acids
- pyrophosphoric acid PPi
- a molecule of adenosine triphosphate (ATP) and L-amino acid (L-AA) acts on AARS one by one, so that aminoacyl adenylic acid (aminoacyl AMP) ⁇ It forms a reaction intermediate called AARS complex.
- aminoacyl AMP usually binds strongly to AARS. Therefore, the above AARS reaction is not allowed to proceed unless tRNA or a nucleophile (amines) is added to decompose the complex.
- Non-patent Document 4 when a large amount of pyrophosphate is produced in the reaction formula 1 of the reaction, the aminoacyl AMP-AARS complex, which is the reverse reaction of the reaction formula 1, is decomposed by pyrophosphate, and amino acids, AARS, and ATP are produced. It is known that an ATP-PPi exchange reaction occurs (Non-patent Document 4).
- Patent Document 3 describes an amino acid analysis method based on the reaction represented by the following reaction formula 3.
- L-amino acid is analyzed by using as an index pyrophosphoric acid generated when AARS binds to ATP and L-amino acid.
- AARS reacts with one molecule of L-amino acid and ATP to produce one molecule of aminoacyl AMP. Therefore, the amount is less than or equal to the L-amino acid in the sample. Only pyrophosphoric acid is produced (Non-Patent Documents 5, 6, and 7).
- Reaction Formula 3 it is described that AARS functions as a catalyst and ATP and L-amino acid react with each other molecule to produce aminoacyl AMP and pyrophosphoric acid. Since tRNA is not contained in the reaction system, reaction formula 2 does not proceed, and it is considered that an aminoacyl AMP-AARS complex is actually formed by reaction formula 1 (Patent Document 2, paragraph number 0013). ⁇ 0016). As a result, it is considered that only one molecule of pyrophosphate is produced from one molecule of AARS. Therefore, in addition to the above-mentioned part of Patent Document 2, it is necessary that a large amount of AARS is required to enable L-amino acid contained in a sample to be quantified by measuring pyrophosphate. It is also recognized by the inventors themselves (paragraph number 0046 of patent document 3, non-patent document 5). *
- the amino acid quantification range of the method is 300 ⁇ M to 900 ⁇ M in the ion sensitive field effect transistor (ISFET) method, which is a high concentration region of amino acids.
- ISFET ion sensitive field effect transistor
- quantification in the range of 1 ⁇ M to 250 ⁇ M is possible only by performing high-sensitivity analysis by a fluorescence method using a multi-step enzyme reaction ( Non-patent documents 6, 7, 8).
- Patent Document 2 discloses a method for quantifying L-amino acids based on the AARS reaction of Reaction Formulas 1 and 2. That is, as described above, aminoacyl AMP usually binds strongly to AARS to form an aminoacyl AMP-AARS complex. Therefore, in this method, by adding amines (nucleophile) such as hydroxylamine as an aminoacyl AMP-AARS complex decomposition reagent, AARS can be reacted again, and as a result, L- It is characterized by quantifying amino acids. The quantitative range of amino acids in the method is said to be 5 ⁇ M to 200 ⁇ M.
- the complex decomposition reagent reacts with the L-amino acid of the complex to produce a compound (for example, as shown in paragraph No. 0037 of Patent Document 2,
- hydroxylamine is used as a biodegradation reagent, “amino acid hydroxamic acid” is produced)
- L-amino acids cannot be reused.
- production of the same amount as L-amino acids in the sample can be achieved.
- Only biological pyrophosphate can be obtained (paragraph number 0023 of Patent Document 2).
- this method is complicated because pyrophosphate generated in the AARS reaction is detected by a multi-stage enzyme reaction, and each enzyme is likely to be affected by contaminants in the blood and other external factors. Concerned.
- AARS reaction for example, the following reactions 4 and 5 are known.
- ATP and L-amino acid act on AARS one molecule at a time to form an aminoacyl AMP-AARS complex.
- diadenosine polyphosphate ApnA
- Ap4A diadenosine tetraphosphate
- Ap4G adenosine anosine tetraphosphate
- Non-patent Document 11 relates to AARS acting on a D-amino acid and passing it to tRNA, and is not intended to solve a technical problem related to the quantification of D-amino acid. Actually, the document does not mention anything about the quantification of D-amino acid utilizing the AARS reaction of the above reaction formulas 4 and 5, and the reuse of the D-amino acid and AARS generated in the reaction formula 5 Is not mentioned at all.
- JP 2013-146264 A Japanese Patent No. 5305208 JP 2011-50357 A JP 2000-69990 A Japanese Patent No. 3135649
- the present invention solves the various problems in the prior art relating to the L-form and D-form amino acid quantification methods described above, and uses AARS to selectively select the L-form and / or D-form amino acids to be measured.
- An object is to provide a simple and highly sensitive quantification method and an amino acid quantification kit.
- the inventors have determined that the aminoacyl tRNA from the aminoacyl AMP-AARS complex once formed in the method for quantifying the amount of amino acids in a sample using AARS, as shown in FIG.
- AARS synthase
- amino acids L-AA and / or D-AA
- reaction products such as those can be produced up to the number of moles greater than the amino acids contained in a sample.
- Step (I) including the following steps: (Step I-1) L-form and / or D-form amino acid (L-AA and / or D-AA) in a sample in the presence of a divalent ion or polyamine, and an aminoacyl-tRNA synthetase (AARS) corresponding to the amino acid And a reaction (reaction 1) of reacting adenosine triphosphate (ATP) to form a complex (aminoacyl AMP-AARS complex) composed of aminoacyl adenylic acid (aminoacyl AMP) and AARS; (Step I-2) The aminoacyl AMP-AARS complex formed in Reaction 1 and / or Reaction 3 is reacted with nucleotides to release AARS and amino acids (L-AA and / or D-AA) from the complex.
- Reaction 1 and / or Reaction 3 The aminoacyl AMP-AARS complex formed in Reaction 1 and / or Reaction 3 is reacted with nucleotides to release
- Step I-2 Reaction for forming an aminoacyl AMP-AARS complex reaction by reusing the amino acid (L-AA and / or D-AA) and / or AARS released in Reaction 2 in Reaction 1 (Reaction 3) comprising: and (Step I-4) Steps I-2 and I-3 are repeated, and Measuring the amount of the reaction product produced in step (I), and determining the amount of L-form and / or D-form amino acids based on the measured amount of the reaction product (II), A method for quantifying amino acids in a sample, comprising: [2] The amount of the reaction product generated in the step (I) is measured by measuring a potential change with an ion-sensitive field effect transistor, a glass electrode, or a multi-electrode potential meter.
- Amino acid quantification method [3] The amino acid quantification method according to [1], wherein the amount of the reaction product generated in step (I) is measured by measuring a change in absorbance by an absorbance method. [4] The amino acid quantification method according to any one of [1] to [3], wherein at least one of pyrophosphate and hydrogen ions is measured as a reaction product generated in the step (I). [5] The amino acid quantification method according to any one of [1] to [4], wherein the number of moles of the reaction product generated in step (I) is larger than the number of moles of amino acids in the sample. .
- amino acid quantification method according to any one of [1] to [5], wherein any one of L-form and D-form amino acids in the sample is removed as pretreatment.
- AARS and amino acids are liberated from the formed aminoacyl AMP-AARS complex, and they are formed into an aminoacyl AMP-AARS complex.
- a reaction product such as pyrophosphate, which is a measurement target, can be produced up to the number of moles more than the amino acid contained in the sample.
- amino acids in a lower concentration range can be quantified. Furthermore, it is possible to quantify both L-form and D-form amino acids. It is also possible to measure the remaining amino acid by AARS after removing any one of the L-form and D-form amino acids.
- an amino acid, AARS and ATP corresponding to the amino acid are reacted to form an aminoacyl AMP-AARS complex.
- the AARS used in the method of the present invention uses AARS that specifically acts on 20 types of amino acids. For example, if it is histidine (His), if it is AARS (HisRS) that acts specifically on histidine, if it is serine (Ser), if it is AARS (SerRS) that specifically acts on serine, tryptophan (Trp), Examples include AARS (TrpRS) that specifically acts on tryptophan.
- the AARS used in the present invention is derived from organisms such as animals such as cattle, rats and mice, plants derived from Lupin seed, Phaseolus aurus, microorganisms such as Escherchia, Thermus, Thermotoga, and Saccharomyces. Any AARS may be used as long as it is AARS, and microorganism-derived AARS is particularly preferable from the viewpoint of handling and productivity. Further, it may be a recombinant AARS or a synthesized AARS.
- a soluble enzyme is preferable, but a surfactant may be combined with the insoluble enzyme, and an enzyme in which the insoluble enzyme is solubilized by fusion with a solubilized protein or deletion of a membrane-bound portion may be used.
- the known amino acid sequence of AARS can be used, and recombinant AARS has a sequence having identity of 60%, 65%, 70%, 75%, 80%, 85%, 90% or 95% or more A protein having AARS activity may be used.
- any method / means known to those skilled in the art for example, water added to an object containing AARS, crushed by a pulverizer, an ultrasonic crusher, etc. and then crushed An extract obtained by removing solid matter by centrifugation, filtration or the like, and AARS purified and isolated from the extract by column chromatography or the like can be used. That is, the main technical feature of the present invention is that, in the amino acid quantification method using AARS, AARS and amino acids are liberated from the formed aminoacyl AMP-AARS complex, and these are released from the aminoacyl AMP-AARS complex. By repeatedly using for formation, reaction products such as pyrophosphate, which is a measurement target, are produced to a number of moles greater than the amino acid contained in the sample, and the method for preparing AARS is not limited in any way Absent.
- the amino acid concentration in each sample varies with each amino acid.
- the amino acid concentration in blood is 11-44 nmol / mL for glutamic acid, 19-33 nmol / mL for methionine, 41-66 nmol / mL for tryptophan, 50-83 nmol / mL for tyrosine, and 92-92 for serine.
- nmol / mL 162 nmol / mL, histidine is 68 to 97 nmol / mL, lysine is 119 to 257 nmol / mL, glutamine is 488 to 733 nmol / mL, alanine is 240 to 510 nmol / mL, and the like.
- the free amino acid content in fresh food is, for example, 5 mg / 100 g for lysine, 136 mg / 100 g for arginine, 6 mg / 100 g for serine, and the like.
- glutamine is 94 mg / 100 g
- proline is 106 mg / 100 g, and the like.
- glutamic acid is 386 mg / 100 g
- threonine is 268 mg / 100 g
- serine is 46 mg / 100 g
- the L-form and D-form amino acid contents of fruit are 2071 ⁇ mol / L for L-form asparagine, 15 ⁇ mol / L for D-form asparagine, and 105 ⁇ mol / L for L-form alanine.
- Alanine is 3 ⁇ mol / L
- pineapple is L asparagine is 3109 ⁇ mol / L
- D asparagine is 25 ⁇ mol / L
- L valine is 202 ⁇ mol / L
- D valine is 2 ⁇ mol / L, etc. is there.
- the content of free amino acids in processed foods and beverages is, for example, 213 mg / 100 g for lysine, 104 mg / 100 g for histidine, 782 mg / 100 g for glutamic acid, etc. for soy sauce.
- serine is 107 mg / 100 g
- arginine is 314 mg / 100 g
- glutamic acid is 258 mg / 100 g, and the like.
- lysine is 10 mg / 100 g
- histidine is 48 mg / 100 g
- serine is 43 mg / 100 g, and the like.
- it can be appropriately diluted and used as the sample of the present invention.
- L-form and D-form may be mixed in the amino acid in the sample used in the present invention.
- any method known to those skilled in the art, such as column chromatography or removal of either the L-form or D-form amino acid by an appropriate enzyme can be mentioned.
- L-form and D-form are mixed, but most D-form amino acids in the mammalian body are about 0.1 to 1.0% of L-form amino acids.
- D-form amino acids are It is 3.0% or less of the L-form amino acid, and the D-form amino acid content in the biological sample is not contained so as to affect the quantification of the L-form amino acid.
- the AARS concentration in the reaction solution used for the reaction is appropriately determined by a person skilled in the art depending on the type of sample, the estimated amino acid concentration in the sample, the ATP concentration, and various reaction conditions such as reaction time and temperature. It is done.
- the amino acid concentration in the sample is expected to be low, it is preferable to increase the AARS concentration. If the concentration is expected to be high, the AARS concentration may be low. Further, the reaction can be completed in a short time by increasing the AARS concentration. Conversely, when the reaction time may be a long time, the AARS concentration may be low.
- the concentration of AARS derived from microorganisms such as Escherchia, Thermus, and Thermotoga is 0.05 ⁇ M or more, more preferably 0.1 ⁇ M or more, further preferably 0.5 ⁇ M or more, particularly preferably 1.0 ⁇ M or more, most preferably Preferably, it can be 5.0 ⁇ M or more.
- AARS is repeatedly used in the method of the present invention, there is an advantage that it is not necessary to add an excessive amount of AARS to the expected amount of amino acids in the sample. Therefore, the upper limit of the AARS concentration can be appropriately set by those skilled in the art in consideration of economics and the like.
- reaction 1 or reaction 3 of the method of the present invention ATP and divalent ions are used together with AARS.
- ATP used in the present invention
- sodium salt, lithium salt and the like can be used.
- concentration of ATP in the reaction solution used for the reaction depends on the type of sample, the expected amino acid concentration in the sample, AARS concentration, nucleotide concentration, and various reaction conditions such as reaction time and temperature. Although a trader is appropriately determined, it is preferable to add ATP so as to be excessive with respect to the expected amino acid concentration in the sample.
- the ATP concentration should be 0.05 mM or more, more preferably 0.1 mM or more, still more preferably 1.0 mM or more, particularly preferably 5.0 mM or more, and most preferably 10.0 mM or more. Can do.
- the upper limit of the ATP concentration can be appropriately set by those skilled in the art in consideration of economics and the like.
- magnesium, manganese, cobalt, calcium etc. can be used for the divalent ion used for this invention. Since divalent ions have different requirements depending on AARS, divalent ions suitable for the AARS to be used may be used as appropriate. However, it is more preferable to use magnesium and manganese which are commonly required for AARS.
- the concentration of the divalent ions in the reaction solution used for the reaction can be determined as appropriate, but it is preferable to add the same or higher than the ATP concentration.
- the ATP: divalent ion ratio in AARS derived from microorganisms such as Escherchia, Thermus, and Thermotoga is at least 1: 1, more preferably at least 1: 3, more preferably at least 1: 5, particularly preferably It can be at least 1: 7, most preferably at least 1:10.
- the aminoacyl AMP-AARS complex formed in the reaction 1 and / or the reaction 3 is reacted with nucleotides, the complex is decomposed, and the AARS and amino acids are converted from the complex. Release.
- the nucleotide used in the reaction is a kind arbitrarily selected from ATP, adenosine diphosphate (ADP), adenosine monophosphate (AMP), guanosine triphosphate (GTP), deoxyadenosine triphosphate (dATP), and the like. Or a combination thereof can be used.
- AMP, Ap4A, Ap3A, Ap4G, Ap3G and the like are generated according to the nucleotide used together with the release of AARS and amino acid from the aminoacyl AMP-AARS complex.
- the nucleotide concentration in the reaction solution used for the reaction is determined by those skilled in the art according to various reaction conditions such as the type of sample, the expected amino acid concentration, AARS concentration, ATP concentration and reaction time / temperature in the sample. Although it is determined as appropriate, it is consumed in the production of AMP, Ap4A, Ap3A, Ap4G, Ap3G and the like. Therefore, it is preferable to add nucleotides so as to be excessive with respect to the amino acid concentration in the sample.
- the nucleotide concentration is 0.05 mM or more, more preferably 0.1 mM or more, still more preferably 1.0 mM or more, particularly preferably 5.0 mM or more, and most preferably 10.0 mM or more. be able to. Therefore, in the method of the present invention, it is not necessary to add an aminoacyl AMP-AARS complex decomposing reagent such as amines as described in Patent Document 2 in order to make AARS reactable again. Since the free amino acid does not react with the reagent, the free amino acid can be used again to form an aminoacyl AMP-AARS complex.
- the aminoacyl AMP-AARS complex reaction is formed by using again the amino acid and / or AARS released in reaction 2 in reaction 1. Furthermore, in step (I) of the method of the present invention, phosphoenolpyruvate and pyruvate dikinase are reacted with pyrophosphate generated in reaction 1 or 3 and AMP in the reaction system by any method known to those skilled in the art.
- the ATP produced by the reaction is reused for aminoacyl AMP-AARS complex formation and liberation of AARS and amino acids from the complex, and / or Ap4A pyrophosphoric acid against Ap4A produced from nucleotides in reaction 2.
- ADP produced by the action of hydrase can also be reused as nucleotides in reaction 2.
- the reaction product of each reaction product such as pyrophosphate and / or hydrogen ion as a result of the reaction in step (I).
- a number of moles of molecules greater than the number of moles of the amino acid to be measured contained in the sample can be produced.
- the method of the present invention it is possible to quantify from an extremely low amino acid concentration of about 1 ⁇ M, which is a lower concentration than in the prior art. Therefore, this point can be said to be a remarkable effect of the present invention as compared with the prior art.
- the amount of pyrophosphate and hydrogen ions produced in the step (I) of the present invention is as long as the amino acid can be quantified by an appropriate measurement method of the reaction product in the step (II).
- the number of repetitions of reaction 2 (step I-2) and reaction 3 (step I-3) in (step I-4) of the method of the present invention is also the same as the reaction product in step (II).
- the amino acid can be quantified by an appropriate method for measuring an organism.
- the reaction temperature in step (I) of the method of the present invention may be any temperature at which each reaction occurs.
- the temperature is preferably 10 to 80 ° C., more preferably 20 to 65 ° C., and most preferably 30 to 60 ° C.
- the temperature is preferably 10 to 100 ° C., more preferably 30 to 98 ° C., and most preferably 50 to 95 ° C.
- the reaction time may be any time that causes an AARS reaction with the amino acid in the sample, but is preferably about 1 to 90 minutes, more preferably about 5 to 60 minutes, and further preferably about 10 to 30 minutes.
- the reaction pH may be any pH that causes an AARS reaction with an amino acid in the sample.
- the pH is preferably 4.0 to 10.0, more preferably 5.0 to 9.8, and most preferably 6.0 to 9.5.
- the reaction pH can be adjusted using any buffering agent known to those skilled in the art.
- reaction components such as reagents and enzymes used in each step included in step (I) of the method of the present invention are added to the reaction system by any means and procedure known to those skilled in the art as long as they are addition methods that cause an AARS reaction. Can be added.
- each component may be added in advance to the reaction system at one time before starting the reaction, or AARS or an amino acid may be added last and allowed to react.
- step (II) of the method of the present invention the amount of each reaction product such as pyrophosphate, adenosine monophosphate (AMP) and hydrogen ion generated in step (I) is measured, and the reaction product is measured.
- the amount of amino acid is determined based on the amount.
- the reaction of the amino acid in the sample and AARS in step (I) is added to the reaction system, for example, as described in the Examples, depending on the measurement method and the like.
- the reaction can be appropriately carried out after the reaction is stopped by any method / means known to those skilled in the art, such as, or at any stage in which the reaction in the step (I) is in progress.
- any method / means known to those skilled in the art for example, molybdenum for measuring the absorbance of a blue complex produced by reacting molybdic acid with pyrophosphoric acid.
- molybdenum for measuring the absorbance of a blue complex produced by reacting molybdic acid with pyrophosphoric acid.
- pyrophosphate such as blue method, hypoxanthine-guanine phosphoribosyltransferase, xanthine oxidase or xanthine dehydrogenase combined method, luminol combined with inorganic pyrophosphatase, pyruvate oxidase and peroxidase Enzymatic methods can be used.
- a measurement method in which an oxidation-reduction reaction is caused by an enzyme reaction or the like and a potential change is measured by a multi-electrode potential meter that detects a current value derived from the oxidation-reduction reaction can be used.
- generated by the said reaction can use the measuring method etc. which measure an electrical potential change with the glass electrode which detects hydrogen ion, or an ion sensitive field effect transistor.
- measurement with an AMP sensor using luminescence that detects adenosine monophosphate can be used.
- Pyrophosphate, hydrogen ions, AMP and the like generated in step (I) of the present invention can be separated from the reaction solution and measured.
- the method for separating pyrophosphoric acid, hydrogen ions, AMP, etc. from the reaction solution is not particularly limited as long as it does not affect the measurement. For example, protein removal by acid treatment, paper chromatography separation, microfluidic device Separation and the like.
- the main technical feature of the present invention is that in the amino acid quantification method using AARS, AARS and an amino acid are released from the formed aminoacyl AMP-AARS complex, and these compounds are formed again.
- the reaction product such as pyrophosphate, which is the measurement target is produced up to the number of moles larger than the amino acid contained in the sample, and the method for measuring the amount of the reaction product is not limited at all. It is not something.
- the present invention provides an amino acid quantification kit for carrying out the above-described method of the present invention, comprising the aforementioned components necessary for quantification of amino acids in a sample.
- the kit may appropriately contain other optional components known to those skilled in the art, such as a stabilizer or a buffer, to enhance the stability of the reagent components such as the enzyme.
- a stabilizer or a buffer to enhance the stability of the reagent components such as the enzyme.
- bovine serum albumin BSA
- antioxidant antioxidant
- surfactant or amino acids etc. which do not have an activity with an enzyme
- the kit for measuring the above-mentioned pyrophosphoric acid and a hydrogen ion can be mentioned as an example of the said kit.
- Example 1 Escherichia coli BL21 (DE3) pLys was transformed with a plasmid (pET28b) having an AARS sequence derived from the Thermus and Thermotoga genera and used as an expression strain.
- Each expression strain was cultured at 37 ° C. in a TB medium containing kanamycin and chloramphenicol as selection markers, and after reaching OD600 of about 0.6, IPTG was added to a final concentration of 1 mM, and at 25 ° C. Evening induction culture was performed. After completion of the culture, the cells were collected, and the obtained cells were sonicated to prepare a cell-free extract.
- the prepared cell-free extract was heat-treated at 70 ° C. for 15 minutes, and then centrifuged. Expression of the target enzyme was confirmed by electrophoresis using a part of the obtained supernatant. Subsequently, HisRS, SerRS, TrpRS, and LysRS were obtained by removing contaminating proteins from the remaining supernatant using a His tag column (trade name: TALON superflow, manufactured by GE Healthcare).
- Escherichia coli BL21 (DE3) pLys was transformed with a plasmid (pET28b) having an AARS sequence derived from E. coli K12 and used as an expression strain.
- Each expression strain was cultured at 37 ° C. in TB medium containing kanamycin and chloramphenicol as selection markers. After reaching OD600 of about 0.6, IPTG was added to a final concentration of 1 mM, and IPTG was added. Induction culture was performed overnight at 25 ° C. After completion of the culture, the cells were collected, and the obtained cells were sonicated to prepare a cell-free extract.
- Example 3 (Production amount of pyrophosphate by various AARS concentrations using L-amino acid: step (I) of the method of the present invention) [Example 3] Prepare 240 ⁇ L of a reaction solution containing 250 mM HEPES-KOH (pH 8), 31.3 mM ATP, 313 mM MgCl 2, 30 ⁇ L of L-histidine to a final concentration of 30 ⁇ M, and HisRS (derived from thermophile) 0.1 ⁇ M. Then, 30 ⁇ L was added and treated at 70 ° C. for 30 minutes. After the reaction, 60 ⁇ L of trichloroacetic acid was added to a final concentration of 4% to stop the reaction. After stopping the reaction, the precipitate was removed by centrifugation to prepare a product (product of the present invention) 1.
- Example 4 Prepare 240 ⁇ L of a reaction solution containing 250 mM HEPES-KOH (pH 8), 31.3 mM ATP, 313 mM MgCl 2, and add 30 ⁇ L of L-histidine to a final concentration of 30 ⁇ M, and HisRS (derived from E. coli) 0.12 ⁇ M, or , 0.17 ⁇ M, or 0.21 ⁇ M, and 30 ⁇ L was added, followed by treatment at 50 ° C. for 30 minutes. After the reaction, 60 ⁇ L of trichloroacetic acid was added to a final concentration of 4% to stop the reaction. After stopping the reaction, the precipitate was removed by centrifugation to prepare Examples 2, 3, and 4.
- Example 5 Prepare 240 ⁇ L of a reaction solution containing 250 mM HEPES-KOH (pH 8), 31.3 mM ATP, 313 mM MgCl 2, 30 ⁇ L of L-serine to a final concentration of 30 ⁇ M, and SerRS (derived from thermophile) at a final concentration of 0.05 ⁇ M.
- 30 ⁇ L was added to a concentration of 0.075 ⁇ M or 0.1 ⁇ M, and the mixture was treated at 70 ° C. for 30 minutes.
- 60 ⁇ L of trichloroacetic acid was added to a final concentration of 4% to stop the reaction. After stopping the reaction, the precipitate was removed by centrifugation to prepare Examples 5, 6, and 7.
- Example 6 Prepare 240 ⁇ L of a reaction solution containing 250 mM HEPES-KOH (pH 8), 31.3 mM ATP, 313 mM MgCl 2, and add L-serine to a final concentration of 30 ⁇ M, SerRS (derived from E. coli) to a final concentration of 0.12 ⁇ M, or , 0.17 ⁇ M, or 0.21 ⁇ M, and 30 ⁇ L was added, followed by treatment at 50 ° C. for 30 minutes. After the reaction, 60 ⁇ L of trichloroacetic acid was added to a final concentration of 4% to stop the reaction. After stopping the reaction, the precipitate was removed by centrifugation, and working products 8, 9, and 10 were prepared.
- Step (I) of the method of the present invention [Example 8] Prepare 240 ⁇ L of a reaction solution containing 250 mM HEPES-KOH (pH 8), 6.3 mM ATP, 63.5 mM MgCl 2, and 250 mM HEPES-KOH (pH 8), 31.3 mM ATP, 313 mM MgCl 2, and add L-histidine to each final concentration. 30 ⁇ L was added to 30 ⁇ M, and 30 ⁇ L of HisRS (derived from thermophilic bacteria) was added to a final concentration of 5 ⁇ M, followed by treatment at 70 ° C. for 15 minutes. After the reaction, 60 ⁇ L of trichloroacetic acid was added to a final concentration of 4% to stop the reaction. After stopping the reaction, the precipitate was removed by centrifugation to prepare Examples 11 and 12.
- Example 9 Prepare 240 ⁇ L of a reaction solution containing 250 mM HEPES-KOH (pH 8), 12.5 mM ATP, 125 mM MgCl 2 and 250 mM HEPES-KOH (pH 8), 31.3 mM ATP, 313 mM MgCl 2, and add L-tyrosine to a final concentration of 30 ⁇ M.
- 30 ⁇ L of TyrRS (derived from E. coli) was added to a final concentration of 5 ⁇ M and treated at 50 ° C. for 30 minutes. After the reaction, 60 ⁇ L of trichloroacetic acid was added to a final concentration of 4% to stop the reaction. After stopping the reaction, the precipitate was removed by centrifugation to prepare Examples 13 and 14.
- Example 10 The prepared pyrophosphoric acids of Examples 11 to 14 were measured by the molybdenum blue method described in Example 7. As a result, as shown in FIG. 3, an increasing tendency of pyrophosphate was observed with an increase in the concentration of ATP. Moreover, when all the added amino acids were used for the enzymatic reaction, more pyrophosphate was produced than the theoretical value of the amount of pyrophosphate produced. Therefore, according to the method of the present invention, it was shown that pyrophosphoric acid having a mole number larger than the number of amino acid molecules contained in the sample was produced.
- Step (I) of the method of the present invention [Example 11] Prepare 240 ⁇ L of a reaction solution containing 250 mM HEPES-KOH (pH 8), 31.3 mM ATP, 31.3 mM MgCl 2, MnCl 2, or CoCl 2, and add 30 ⁇ L of SerRS (E. coli) to a final concentration of 30 ⁇ M. Origin) was added to a final concentration of 5 ⁇ M, and treated at 50 ° C. for 30 minutes. After the reaction, 60 ⁇ L of trichloroacetic acid was added to a final concentration of 4% to stop the reaction. After stopping the reaction, the precipitate was removed by centrifugation, and working products 15 to 17 were prepared.
- Example 12 240 ⁇ L of a reaction solution containing 250 mM HEPES-KOH (pH 8), 31.3 mM ATP, 31.3 mM MgCl 2, MnCl 2 or CoCl 2 was prepared, and 30 ⁇ L of L-tyrosine was added to a final concentration of 30 ⁇ M. Origin) was added to a final concentration of 5 ⁇ M, and treated at 50 ° C. for 30 minutes. After the reaction, 60 ⁇ L of trichloroacetic acid was added to a final concentration of 4% to stop the reaction. After stopping the reaction, the precipitate was removed by centrifugation to prepare practical products 18-20.
- Example 13 Prepare 240 ⁇ L of a reaction solution containing 250 mM HEPES-KOH (pH 8), 31.3 mM ATP, 31.3 mM MgCl 2, MnCl 2, or CoCl 2, and add 30 ⁇ L of His-RS (preferred) to a final concentration of 30 ⁇ M L-histidine. 30 ⁇ L of thermobacteria) was added to a final concentration of 5 ⁇ M and treated at 70 ° C. for 30 minutes. After the reaction, 60 ⁇ L of trichloroacetic acid was added to a final concentration of 4% to stop the reaction. After stopping the reaction, the precipitate was removed by centrifugation to prepare Examples 21 to 23.
- Example 14 Prepare 240 ⁇ L of a reaction solution containing 250 mM HEPES-KOH (pH 8), 31.3 mM ATP, 31.3 mM MgCl 2, MnCl 2, or CoCl 2, and add 30 ⁇ L of SerRS (preferably) to a final concentration of 30 ⁇ M.
- 30 ⁇ L of thermobacteria was added to a final concentration of 5 ⁇ M and treated at 70 ° C. for 30 minutes. After the reaction, 60 ⁇ L of trichloroacetic acid was added to a final concentration of 4% to stop the reaction. After stopping the reaction, the precipitate was removed by centrifugation to prepare practical products 24-26.
- Example 15 (Measurement of pyrophosphate by molybdenum blue method: step (II) of the method of the present invention) [Example 15]
- Examples 15 to 26 prepared in Examples 11 to 14 were measured by the molybdenum blue method described in Example 7.
- FIG. 4 it was shown that the amount of pyrophosphate produced varies with the same AARS depending on the type of divalent cation.
- Mg and Mn are optimum divalent ions that are commonly required for AARS.
- Example 17 Prepare a reaction solution containing 250 mM HEPES-KOH (pH 8), 31.3 mM ATP, 313 mM MgCl2, or 240 ⁇ L of a reaction solution containing 250 mM HEPES-KOH (pH 8), 31.3 mM ATP, 31.3 mM ADP, 313 mM MgCl2, 30 ⁇ L of L-histidine was added to a final concentration of 50 ⁇ M, and 30 ⁇ L of HisRS (derived from E. coli) was added to a final concentration of 5 ⁇ M, followed by treatment at 50 ° C. for 30 minutes. After the reaction, 60 ⁇ L of trichloroacetic acid was added to a final concentration of 4% to stop the reaction. After stopping the reaction, the precipitate was removed by centrifugation to prepare practical products 30 and 31.
- Example 18 A reaction solution containing 250 mM HEPES-KOH (pH 8), 31.3 mM ATP, 313 mM MgCl2, or 240 ⁇ L of a reaction solution containing 250 mM HEPES-KOH (pH 8), 31.3 mM ATP, 31.3 mM AMP, 313 mM MgCl2, 30 ⁇ L of L-tyrosine was added to a final concentration of 50 ⁇ M, and 30 ⁇ L of TyrRS (derived from E. coli) was added to a final concentration of 5 ⁇ M, followed by treatment at 50 ° C. for 30 minutes. After the reaction, 60 ⁇ L of trichloroacetic acid was added to a final concentration of 4% to stop the reaction. After stopping the reaction, the precipitate was removed by centrifugation to prepare practical products 32 and 33.
- Example 20 150 ⁇ L of a reaction solution containing 5.2 ⁇ M HisRS (derived from thermophile), 50 ⁇ M L-histidine, 25.9 mM ATP, 259 mM MgCl 2 and 20 mM HEPES-KOH (pH 8) was prepared, and an enzyme reaction was performed at 70 ° C. for 30 minutes. . After the enzyme reaction, 30 ⁇ L of trichloroacetic acid was added to a final concentration of 4% to stop the reaction. After stopping the reaction, the precipitate was removed by centrifugation to prepare a product 34.
- HisRS derived from thermophile
- 50 ⁇ M L-histidine 50 ⁇ M L-histidine
- 25.9 mM ATP 25.9 mM ATP
- 259 mM MgCl 2 20 mM HEPES-KOH (pH 8) was prepared, and an enzyme reaction was performed at 70 ° C. for 30 minutes.
- Example 21 150 ⁇ L of a reaction solution containing 5.1 ⁇ M SerRS (derived from thermophile), 50 ⁇ M L-serine, 25.6 mM ATP, 256 mM MgCl2, 20 mM HEPES-KOH (pH 8) was prepared, and an enzyme reaction was performed at 70 ° C. for 30 minutes. . After the enzyme reaction, 30 ⁇ L of trichloroacetic acid was added to a final concentration of 4% to stop the reaction. After stopping the reaction, the precipitate was removed by centrifugation to prepare a product 35.
- SerRS derived from thermophile
- 50 ⁇ M L-serine 50 ⁇ M L-serine
- 25.6 mM ATP 25.6 mM ATP
- 256 mM MgCl2 20 mM HEPES-KOH (pH 8) was prepared, and an enzyme reaction was performed at 70 ° C. for 30 minutes.
- 30 ⁇ L of trichloroacetic acid was
- Example 22 150 ⁇ L of a reaction solution containing 4.4 ⁇ M LysRS (derived from thermophile), 50 ⁇ M L-lysine, 22 mM ATP, 220 mM MgCl 2 and 20 mM HEPES-KOH (pH 8) was prepared, and an enzyme reaction was performed at 70 ° C. for 30 minutes. After the enzyme reaction, 30 ⁇ L of trichloroacetic acid was added to a final concentration of 4% to stop the reaction. After stopping the reaction, the precipitate was removed by centrifugation to prepare a product 36.
- LysRS derived from thermophile
- Example 23 The pyrophosphoric acids of Comparative Examples 1 to 3 and Examples 34 to 36 obtained in Comparative Examples 1 to 3 and Examples 20 to 22 were measured by the molybdenum blue method described in Example 7. As a result, as shown in FIG. 6, the method of the present invention produced more pyrophosphate than the theoretical amount of pyrophosphate estimated to be produced when all the added amino acids were used in the reaction. . On the other hand, the comparative product was less than the theoretical value. This shows that the number of molecules of pyrophosphate produced by the conventional measurement method using AARS is less than the number of amino acid molecules, but the method of the present invention produces more pyrophosphate than the number of amino acid molecules. .
- Example 24 1 ⁇ M HisRS (derived from thermophile), 30 ⁇ M L-histidine, 2 mM ATP, 20 mM MgCl2, 200 mM HEPES-KOH (pH 8), and 5 ⁇ M SerRS (derived from thermophile), 30 ⁇ M L-serine, 2 mM ATP, 6 mM MgCl2, 200 mM 150 ⁇ L of a reaction solution containing HEPES-KOH (pH 8) was prepared, and an enzyme reaction was performed at 70 ° C. for 30 minutes. After the enzyme reaction, 30 ⁇ L of trichloroacetic acid was added to a final concentration of 4% to stop the reaction. After stopping the reaction, the precipitate was removed by centrifugation to prepare Examples 37 and 38.
- Example 25 The pyrophosphoric acid of Comparative Products 4 and 37 and 38 obtained in Comparative Example 4 and Example 24 was measured by the molybdenum blue method described in Example 7. As a result, as shown in FIG. 7, the method of the present invention produced more pyrophosphate than the theoretical amount of pyrophosphate estimated to be produced when all the added amino acids were used in the reaction. On the other hand, the comparison product was less than the theoretical value. Therefore, in the conventional measurement method using AARS using a nucleophile, the number of molecules of pyrophosphate produced is less than the number of amino acid molecules, but in the method of the present invention, more pyrophosphate than the number of amino acid molecules is present. It was shown to be produced.
- Example 26 (Temperature dependence of AARS) [Example 26] To 120 ⁇ L of a reaction solution containing 250 mM HEPES-KOH (pH 8), 31.3 mM ATP, 313 mM MgCl 2, 15 ⁇ L of L-serine is added to a final concentration of 50 ⁇ M, and 15 ⁇ L of SerRS (derived from E. coli) is added to a final concentration of 5 ⁇ M. The enzyme reaction solution was reacted at 10 ° C., 30 ° C., 40 ° C., 45 ° C., 50 ° C., 60 ° C., 70 ° C., and 80 ° C. for 30 minutes.
- pyrophosphate production was observed in the range of 10 ° C. to 80 ° C., and in particular, favorable pyrophosphate production was observed in the range of 30 ° C. to 60 ° C.
- Example 27 To a reaction solution containing 250 mM HEPES-KOH (pH 8), 12.5 mM ATP, and 125 mM MgCl 2, L-histidine is 15 ⁇ L so that the final concentration is 30 ⁇ M, and HisRS (derived from thermophilic bacteria) is 5 ⁇ M.
- the enzyme reaction solution added with 15 ⁇ L was reacted at 10 ° C., 30 ° C., 40 ° C., 50 ° C., 70 ° C., 80 ° C., 90 ° C., and 95 ° C. for 15 minutes. After the reaction, 30 ⁇ L of trichloroacetic acid was added to a final concentration of 4% to stop the reaction.
- Example 28 Preparation of amino acid calibration curve for pyrophosphate measurement by molybdenum blue method.
- Each sample was prepared by adding 15 ⁇ L of L-tyrosine to 120 ⁇ L of a reaction solution containing 250 mM HEPES-KOH (pH 8), 31.3 mM ATP, 313 mM MgCl 2 so that the final concentrations of L-tyrosine were 0 ⁇ M, 30 ⁇ M, 70 ⁇ M, and 100 ⁇ M.
- 15 ⁇ L of TyrRS (derived from E. coli) was added to the sample to a final concentration of 5 ⁇ M, and reacted at 50 ° C. for 30 minutes.
- Example 29 Each sample obtained by adding 15 ⁇ L of L-serine to a final concentration of 0 ⁇ M, 60 ⁇ M, 100 ⁇ M, 150 ⁇ M, 200 ⁇ M, 250 ⁇ M, and 300 ⁇ M to 120 ⁇ L of a reaction solution containing 250 mM HEPES-KOH (pH 8), 31.3 mM ATP, 313 mM MgCl 2
- SerRS derived from thermophilic bacteria
- 30 ⁇ L of trichloroacetic acid was added to a final concentration of 4% to stop the reaction.
- Example 30 Each sample obtained by adding 15 ⁇ L of L-histidine to final concentrations of 0 ⁇ M, 1.0 ⁇ M, 3.0 ⁇ M, and 5.0 ⁇ M to 120 ⁇ L of a reaction solution containing 250 mM HEPES-KOH (pH 8), 31.3 mM ATP, and 313 mM MgCl 2 Then, 15 ⁇ L of HisRS (derived from E. coli) was added to each sample to a final concentration of 5 ⁇ M and reacted at 50 ° C. for 30 minutes. After the reaction, 30 ⁇ L of trichloroacetic acid was added to a final concentration of 4% to stop the reaction.
- HisRS derived from E. coli
- Example 31 Each sample obtained by adding 15 ⁇ L of a reaction solution containing 250 mM HEPES-KOH (pH 8), 31.3 mM ATP, 313 mM MgCl 2 to a final concentration of L-tryptophan of 0 ⁇ M, 1.0 ⁇ M, 3.0 ⁇ M, and 5.0 ⁇ M was added. After the preparation, 15 ⁇ L of TrpRS (derived from thermophilic bacteria) was further added to each sample to a final concentration of 5 ⁇ M, and reacted at 70 ° C. for 30 minutes. After the reaction, 30 ⁇ L of trichloroacetic acid was added to a final concentration of 4% to stop the reaction.
- TrpRS derived from thermophilic bacteria
- Example 33 100 ⁇ L of each sample containing 5 ⁇ M LysRS (derived from thermophile), 0 ⁇ M, 15 ⁇ M, 20 ⁇ M, 40 ⁇ M, 50 ⁇ M L-lysine, 10 mM ATP, 100 mM MgCl2, 1 mM HEPES-KOH (pH 8) as a reaction composition was prepared, The same treatment as in Example 32 was performed.
- Example 34 100 ⁇ L of each sample containing 5 ⁇ M SerRS (derived from thermophile), 0 ⁇ M, 20 ⁇ M, 50 ⁇ M, 60 ⁇ M L-serine, 10 mM ATP, 100 mM MgCl2, 1 mM HEPES-KOH (pH 8) as a reaction composition was prepared. The same treatment as 32 was performed.
- Example 35 Measurement using a physiologically active reaction measuring device (AMIS-101X, manufactured by Bio-X) was performed.
- AMIS-101X an AMIS sensor with built-in reference electrode (AMIS-051) was used.
- the prepared measurement object was placed in the sensing part A in place of the amino acids in the sensing part B.
- Step (I) of the method of the present invention [Example 36] 240 ⁇ L of reaction solution containing 250 mM HEPES-KOH (pH 8), 31.3 mM ATP, 31.3 mM MnCl 2, or 240 ⁇ L of reaction solution containing 250 mM HEPES-KOH (pH 8), 50 mM ATP, 50 mM MnCl 2, or 250 mM HEPES-KOH (PH 8), 240 ⁇ L of a reaction solution containing 62.5 mM ATP and 62.5 mM MnCl 2 is prepared, and 30 ⁇ L of D-histidine is added to a final concentration of 50 ⁇ M, and 30 ⁇ L of HisRS (derived from E.
- Example 37 240 ⁇ L of reaction solution containing 250 mM HEPES-KOH (pH 8), 31.3 mM ATP, 31.3 mM MnCl 2, or 240 ⁇ L of reaction solution containing 250 mM HEPES-KOH (pH 8), 50 mM ATP, 50 mM MnCl 2, or 250 mM HEPES-KOH (PH 8), 240 ⁇ L of a reaction solution containing 62.5 mM ATP and 62.5 mM MnCl 2, 30 ⁇ L of D-tryptophan to a final concentration of 50 ⁇ M and 30 ⁇ L of TrpRS (derived from thermophile) to a final concentration of 5 ⁇ M Added and treated at 70 ° C. for 30 minutes. After the reaction, 60 ⁇ L of trichloroacetic acid was added to a final concentration of 4% to stop the reaction. After stopping the reaction, the precipitate was removed by centrifugation to prepare practical products 42 to 44.
- TrpRS
- Example 39 Preparation of calibration curve with D-amino acid in pyrophosphoric acid measurement by molybdenum blue method.
- Each sample was prepared by adding 15 ⁇ L of D-tyrosine to a final concentration of 0 ⁇ M, 3 ⁇ M, 5 ⁇ M, and 10 ⁇ M in 120 ⁇ L of a reaction solution containing 250 mM HEPES-KOH (pH 8), 50 mM ATP, and 50 mM MnCl 2.
- 15 ⁇ L of TyrRS (derived from E. coli) was added to a final concentration of 5 ⁇ M and reacted at 40 ° C. for 30 minutes.
- Example 40 After preparing each sample, 15 ⁇ L of D-histidine was added to 120 ⁇ L of a reaction solution containing 250 mM HEPES-KOH (pH 8), 50 mM ATP, 50 mM MnCl 2 so that D-histidine had a final concentration of 0 ⁇ M, 30 ⁇ M, 50 ⁇ M, 80 ⁇ M, 100 ⁇ M, and 150 ⁇ M. Furthermore, 15 ⁇ L of HisRS (derived from E. coli) was added to each sample to a final concentration of 5 ⁇ M and reacted at 40 ° C. for 30 minutes. After the reaction, 30 ⁇ L of trichloroacetic acid was added to a final concentration of 4% to stop the reaction.
- HisRS derived from E. coli
- Example 42 Each sample was prepared by adding 30 ⁇ L of the amino acid solution prepared in Example 41 to 240 ⁇ L of a reaction solution containing 250 mM HEPES-KOH (pH 8), 50 mM ATP, 50 mM MnCl 2, and then TrpRS (derived from E. coli) was added to each sample at a final concentration. 30 ⁇ L was added to 5 ⁇ M and reacted at 40 ° C. for 30 minutes. After the reaction, 60 ⁇ L of trichloroacetic acid was added to a final concentration of 4% to stop the reaction. After the reaction was stopped, the precipitate was removed by centrifugation to prepare a product 45.
- a reaction solution containing 250 mM HEPES-KOH (pH 8), 50 mM ATP, 50 mM MnCl 2, and then TrpRS (derived from E. coli) was added to each sample at a final concentration. 30 ⁇ L was added to 5 ⁇ M and reacted at 40 ° C. for
- Example 43 Pyrophosphate in the supernatants of Example 45 and Comparative Examples 5 and 6 obtained in Example 42 was measured by the molybdenum blue method described in Example 7. As a result, as shown in FIG. 13, the product 45 and the comparative product 5 had substantially the same amount of pyrophosphate production. From this, it was considered that L-tryptophan in the mixed solution of D-form and L-form tryptophan could be removed by the enzyme treatment. Therefore, it was shown that the D-amino acid in the D-form and L-form amino acid mixture can be measured by removing the L-amino acid.
- the amount of pyrophosphate produced varies depending on the enzyme reaction temperature, and in AARS derived from Escherichia coli and thermophile, an AARS reaction can suitably occur at 10 ° C. to 95 ° C. I understood. Further, as shown in Examples 28 to 31 and Examples 39 and 40, pyrophosphate increases linearly depending on the amino acid concentration in each AARS in any of the L-form and D-form amino acids, ie, amino acids.
- the method of the present invention allows the quantification of amino acids in the concentration range of 1 to 300 ⁇ M, and this range is the high level of the prior art. It was comparable to the amino acid quantification range of 1 to 250 ⁇ M in the amino acid quantification method of sensitivity analysis.
- calibration curves for various amino acids could be prepared using a cumulative ISFET electrode.
- the amino acid quantification range is 0 to 20 ⁇ M, and the concentration range is much lower than the amino acid quantification range of 300 to 900 ⁇ M (90 to 270 ⁇ M in terms of the cumulative ISFET electrode used in the above example) using the conventional ISFET electrode. It was found that quantification of amino acids was possible.
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Abstract
Description
[1]以下の各工程を含む工程(I):
(工程I-1)二価イオン又はポリアミンの存在下、試料中のL体及び/又はD体のアミノ酸(L-AA及び/又はD-AA)、該アミノ酸に対応するアミノアシルtRNA合成酵素(AARS)、及び、アデノシン三リン酸(ATP)を反応させて、アミノアシルアデニル酸(アミノアシルAMP)とAARSから成る複合体(アミノアシルAMP-AARS複合体)を形成させる反応(反応1)を含む工程;
(工程I-2)反応1及び/又は反応3で形成されたアミノアシルAMP-AARS複合体とヌクレオチドを反応させて、該複合体からAARS及びアミノ酸(L-AA及び/又はD-AA)を遊離させる反応(反応2)を含む工程;
(工程I-3)反応2で遊離されたアミノ酸(L-AA及び/又はD-AA)及び/又はAARSを反応1において再利用することによってアミノアシルAMP-AARS複合体反応を形成させる反応(反応3)を含む工程;及び、
(工程I-4)工程I-2及び工程I-3を繰り返す工程、並びに、
工程(I)で生じた反応産生物の量を測定し、該反応産生物の測定量に基づきL体及び/又はD体のアミノ酸の量を決定することを含む工程(II)、
を含む、試料中のアミノ酸定量方法。
[2]イオン感応性電界効果トランジスタ、ガラス電極、又は、多電極電位計測計により電位変化を測定することによって、工程(I)で生じた反応産生物の量を測定する、[1]に記載のアミノ酸定量方法。
[3]吸光度法により吸光度変化を測定することによって、工程(I)で生じた反応産生物の量を測定する、[1]に記載のアミノ酸定量方法。
[4]工程(I)で生じる反応産生物として、ピロリン酸又は水素イオンの少なくとも何れか1つを測定する、[1]~[3]のいずれか一項に記載のアミノ酸定量方法。
[5]工程(I)で生じた反応産生物のモル数が試料中のアミノ酸のモル数より多いことを特徴とする、[1]~[4]のいずれか一項に記載のアミノ酸定量方法。
[6]前処理として、試料中のL体又はD体のアミノ酸の何れか一方を除去することを特徴とする、[1]~[5]のいずれか一項に記載のアミノ酸定量方法。
[7][1]~[6]のいずれか一項に記載のアミノ酸定量法を実施するためのアミノ酸定量用キットであって、ATP、ヌクレオチド及び該アミノ酸に対応するAARSを含む、アミノ酸定量用キット。
[実施例1]
Thermus属及びThermotoga属由来のAARS配列をもつプラスミド(pET28b)で大腸菌BL21(DE3)pLys株を形質転換し、発現株として用いた。各発現株について、選択マーカーとしてカナマイシン、クロラムフェニコールを含むTB培地で37℃培養し、OD600が約0.6に到達後、IPTGを終濃度1mMとなるように添加し、25℃で一晩誘導培養を行った。培養終了後、集菌を行い、得られた菌体を超音波破砕し、無細胞抽出液を調製した。調製した無細胞抽出液を70℃、15分の熱処理を行った後、遠心分離を行った。得られた上清の一部を用いて電気泳動法により目的酵素の発現を確認した。次いで 残りの上清をHisタグカラム(商品名:TALON superflow、GEヘルスケア製)により夾雑タンパクを除去することにより、HisRS、SerRS、TrpRS、LysRSを得た。
大腸菌K12由来のAARS配列をもつプラスミド(pET28b)で大腸菌BL21(DE3)pLys株を形質転換し、発現株として用いた。各発現株について、選択マーカーとしてカナマイシン、クロラムフェニコールを含むTB培地で37℃培養し、OD600が約0.6に到達後、IPTGを終濃度1mMとなるように添加し、IPTGを添加して25℃で一晩誘導培養を行った。培養終了後、集菌を行い、得られた菌体を超音波破砕し、無細胞抽出液を調製した。さらに遠心分離を行い、得られた上清の一部を用いて電気泳動法により目的酵素の発現を確認した。次いで残りの上清をHisタグカラム(商品名:TALON superflow、GEヘルスケア製)により夾雑タンパクを除去することにより、TyrRS、HisRS、SerRS、TrpRSを得た。
[実施例3]
250mM HEPES-KOH(pH8)、31.3mM ATP、313mM MgCl2を含む反応溶液240μLを調製し、L-ヒスチジンを終濃度30μMとなるように30μL、HisRS(好熱菌由来)を終濃度0.1μMとなるように30μL添加し、70℃、30分間処理した。反応後、トリクロロ酢酸を終濃度4%となるように60μL添加し、反応を停止した。反応停止後、遠心分離で沈殿を除去し、実施品(本発明品)1を調製した。
250mM HEPES-KOH(pH8)、31.3mM ATP、313mM MgCl2を含む反応溶液240μLを調製し、L-ヒスチジンを終濃度30μMとなるように30μL、HisRS(大腸菌由来)を終濃度0.12μM、又は、0.17μM、又は、0.21μMとなるように30μL添加し、50℃、30分間処理した。反応後、トリクロロ酢酸を終濃度4%となるように60μL添加し、反応を停止した。反応停止後、遠心分離で沈殿を除去し、実施品2、3、4を調製した。
250mM HEPES-KOH(pH8)、31.3mM ATP、313mM MgCl2を含む反応溶液240μLを調製し、L-セリンを終濃度30μMとなるように30μL、SerRS(好熱菌由来)を終濃度0.05μM、又は、0.075μM、又は、0.1μMとなるように30μL添加し、70℃、30分間処理した。反応後、トリクロロ酢酸を終濃度4%となるように60μL添加し、反応を停止した。反応停止後、遠心分離で沈殿を除去し、実施品5、6、7を調製した。
250mM HEPES-KOH(pH8)、31.3mM ATP、313mM MgCl2を含む反応溶液240μLを調製し、L-セリンを終濃度30μMとなるように30μL、SerRS(大腸菌由来)を終濃度0.12μM、又は、0.17μM、又は、0.21μMとなるように30μL添加し、50℃、30分間処理した。反応後、トリクロロ酢酸を終濃度4%となるように60μL添加し、反応を停止した。反応停止後、遠心分離で沈殿を除去し、実施品8、9、10を調製した。
[実施例7]
調製した実施品1~10の反応溶液150μLに1Mメルカプトエタノール15μL、発色液(2.5%モリブデン酸アンモニウム/5N硫酸)60μLを混合し、室温で20分間静置した後、580nmの吸光度を測定した。なお、L-アミノ酸の代わりに水を添加したサンプルの吸光値を、ブランクとして各サンプルの吸光値から差し引いた値から、反応溶液中のピロリン酸量を求めた。その結果、図2に示す通り、添加したアミノ酸が全て酵素反応に使用された場合に産生されるピロリン酸量の理論値より多くのピロリン酸が産生されていた。従って、本発明の方法によれば、試料中に含まれるアミノ酸分子数より多くのモル数のピロリン酸が産生されることが示された。
[実施例8]
250mM HEPES-KOH(pH8)、6.3mM ATP、63.5mM MgCl2及び250mM HEPES-KOH(pH8)、31.3mM ATP、313mM MgCl2を含む反応溶液240μLを調製し、それぞれにL-ヒスチジンを終濃度30μMとなるように30μL、HisRS(好熱菌由来)を終濃度5μMとなるように30μL添加し、70℃、15分間処理した。反応後、トリクロロ酢酸を終濃度4%となるように60μL添加し、反応を停止した。反応停止後、遠心分離で沈殿を除去し、実施品11及び12を調製した。
250mM HEPES-KOH(pH8)、12.5mM ATP、125mM MgCl2及び250mM HEPES-KOH(pH8)、31.3mM ATP、313mM MgCl2を含む反応溶液240μLを調製し、それぞれにL-チロシンを終濃度30μMとなるように30μL、TyrRS(大腸菌由来)を終濃度5μMとなるように30μL添加し、50℃、30分間処理した。反応後、トリクロロ酢酸を終濃度4%となるように60μL添加し、反応を停止した。反応停止後、遠心分離で沈殿を除去し、実施品13及び14を調製した。
[実施例10]
調製した実施品11~14のピロリン酸を実施例7に記載のモリブデンブルー法により測定した。その結果、図3に示す通り、ATPの濃度の増加と共にピロリン酸の増加傾向が見られた。また、添加したアミノ酸が全て酵素反応に使用された場合に産生されるピロリン酸量の理論値より多くのピロリン酸が産生されていた。従って、本発明の方法によれば、試料中に含まれるアミノ酸分子数より多くのモル数のピロリン酸が産生されることが示された。
[実施例11]
250mM HEPES-KOH(pH8)、31.3mM ATP、31.3mM MgCl2、又は、MnCl2、又は、CoCl2を含む反応溶液240μLを調製し、L-セリンを終濃度30μMとなるように30μL、SerRS(大腸菌由来)を終濃度5μMとなるように30μL添加し、50℃、30分間処理した。反応後、トリクロロ酢酸を終濃度4%となるように60μL添加し、反応を停止した。反応停止後、遠心分離で沈殿を除去し、実施品15~17を調製した。
250mM HEPES-KOH(pH8)、31.3mM ATP、31.3mM MgCl2、又は、MnCl2、又は、CoCl2を含む反応溶液240μLを調製し、L-チロシンを終濃度30μMとなるように30μL、TyrRS(大腸菌由来)を終濃度5μMとなるように30μL添加し、50℃、30分間処理した。反応後、トリクロロ酢酸を終濃度4%となるように60μL添加し、反応を停止した。反応停止後、遠心分離で沈殿を除去し、実施品18~20を調製した。
250mM HEPES-KOH(pH8)、31.3mM ATP、31.3mM MgCl2、又は、MnCl2、又は、CoCl2を含む反応溶液240μLを調製し、L-ヒスチジンを終濃度30μMとなるように30μL、HisRS(好熱菌由来)を終濃度5μMとなるように30μL添加し、70℃、30分間処理した。反応後、トリクロロ酢酸を終濃度4%となるように60μL添加し、反応を停止した。反応停止後、遠心分離で沈殿を除去し、実施品21~23を調製した。
250mM HEPES-KOH(pH8)、31.3mM ATP、31.3mM MgCl2、又は、MnCl2、又は、CoCl2を含む反応溶液240μLを調製し、L-セリンを終濃度30μMとなるように30μL、SerRS(好熱菌由来)を終濃度5μMとなるように30μL添加し、70℃、30分間処理した。反応後、トリクロロ酢酸を終濃度4%となるように60μL添加し、反応を停止した。反応停止後、遠心分離で沈殿を除去し、実施品24~26を調製した。
[実施例15]
実施例11~14で調製した実施品15~26を、実施例7に記載のモリブデンブルー法により測定した。その結果、図4に示す通り、二価陽イオンの種類によって、同じAARSでもピロリン酸産生量が異なることが示された。また、AARSの種類によっても、二価イオンのピロリン酸産生量に対する影響は異なるが、MgやMnがAARS共通に要求性のある最適な二価イオンであることが示された。
[実施例16]
250mM HEPES-KOH(pH8)、31.3mM ATP、313mM MgCl2を含む反応溶液、又は、250mM HEPES-KOH(pH8)、31.3mM ATP、31.3mM ADP、313mM MgCl2を含む反応溶液、又は、250mM HEPES-KOH(pH8)、31.3mM ATP、31.3mM AMP、313mM MgCl2を含む反応溶液240μLを調製し、L-トリプトファンを終濃度50μMとなるように30μL、TrpRS(大腸菌由来)を終濃度5μMとなるように30μL添加し、50℃、30分間処理した。反応後、トリクロロ酢酸を終濃度4%となるように60μL添加し、反応を停止した。反応停止後、遠心分離で沈殿を除去し、実施品27~29を調製した。
250mM HEPES-KOH(pH8)、31.3mM ATP、313mM MgCl2を含む反応溶液又は、250mM HEPES-KOH(pH8)、31.3mM ATP、31.3mM ADP、313mM MgCl2を含む反応溶液240μLを調製し、L-ヒスチジンを終濃度50μMとなるように30μL、HisRS(大腸菌由来)を終濃度5μMとなるように30μL添加し、50℃、30分間処理した。反応後、トリクロロ酢酸を終濃度4%となるように60μL添加し、反応を停止した。反応停止後、遠心分離で沈殿を除去し、実施品30及び31を調製した。
250mM HEPES-KOH(pH8)、31.3mM ATP、313mM MgCl2を含む反応溶液又は、250mM HEPES-KOH(pH8)、31.3mM ATP、31.3mM AMP、313mM MgCl2を含む反応溶液240μLを調製し、L-チロシンを終濃度50μMとなるように30μL、TyrRS(大腸菌由来)を終濃度5μMとなるように30μL添加し、50℃、30分間処理した。反応後、トリクロロ酢酸を終濃度4%となるように60μL添加し、反応を停止した。反応停止後、遠心分離で沈殿を除去し、実施品32及び33を調製した。
[実施例19]
実施例16~18で調製した実施品27~33を、実施例7に記載のモリブデンブルー法により測定した。その結果、図5に示す通り、ATPのみを添加した場合に比べ、ATPとADP、又は、ATPとAMPを添加した場合、ピロリン酸産生量が増加していた。このことから、ADPやAMPはAARS反応に用いられるヌクレオチドとして有効であることが示された。
[比較例1]
非特許文献6記載の反応条件に従い、4.7μM HisRS(好熱菌由来)、50μM L-ヒスチジン、0.2mM ATP、5mM MgCl2、15mM HEPES-KOH(pH8)、10mM KClを含む反応液150μLを調製し、80℃で30分間酵素反応を行った。酵素反応後、トリクロロ酢酸を終濃度4%となるように30μL添加し反応を停止した。反応停止後、遠心分離で沈殿を除去し、比較品1を調製した。
非特許文献7記載の反応条件に従い、3.1μM SerRS(好熱菌由来)、50μM L-セリン、2mM ATP、5mM MgCl2、100mM Tris-HCl(pH8)、10mM KClを含む反応液150μLを調製し、80℃で30分間酵素反応を行った。酵素反応後、トリクロロ酢酸を終濃度4%となるように30μL添加し反応を停止した。反応停止後、遠心分離で沈殿を除去し、比較品2を調製した。
非特許文献6記載の反応条件に従い、4.5μM LysRS(好熱菌由来)、50μM L-リジン、0.2mM ATP、5mM MgCl2、15mM HEPES-KOH(pH8)、10mM KClを含む反応液150μLを調製し、80℃で30分間酵素反応を行った。酵素反応後、トリクロロ酢酸を終濃度4%となるように30μL添加し反応を停止した。反応停止後、遠心分離で沈殿を除去し、比較品3を調製した。
5.2μM HisRS(好熱菌由来)、50μM L-ヒスチジン、25.9mM ATP、259mM MgCl2、20mM HEPES-KOH(pH8)を含む反応液を150μL調製し、70℃で30分間酵素反応を行った。酵素反応後、トリクロロ酢酸を終濃度4%となるように30μL添加し反応を停止した。反応停止後、遠心分離で沈殿を除去し、実施品34を調製した。
5.1μM SerRS(好熱菌由来)、50μM L-セリン、25.6mM ATP、256mM MgCl2、20mM HEPES-KOH(pH8)を含む反応液を150μL調製し、70℃で30分間酵素反応を行った。酵素反応後、トリクロロ酢酸を終濃度4%となるように30μL添加し反応を停止した。反応停止後、遠心分離で沈殿を除去し、実施品35を調製した。
4.4μM LysRS(好熱菌由来)、50μM L-リジン、22mM ATP、220mM MgCl2、20mM HEPES-KOH(pH8)を含む反応液を150μL調製し、70℃で30分間酵素反応を行った。酵素反応後、トリクロロ酢酸を終濃度4%となるように30μL添加し反応を停止した。反応停止後、遠心分離で沈殿を除去し、実施品36を調製した。
比較例1~3及び実施例20~22で得られた比較品1~3及び実施品34~36のピロリン酸を実施例7に記載のモリブデンブルー法により測定した。その結果、図6に示すように本発明の方法では、添加したアミノ酸が全て反応に使用された場合に産生されると推測されるピロリン酸量の理論値より多くのピロリン酸が産生されていた。一方、比較品は、理論値以下であった。このことから、従来のAARSを用いた測定法で産生されるピロリン酸の分子数はアミノ酸分子数より少ないが、本発明方法ではアミノ酸分子数より多くのピロリン酸が産生されることが示された。
[比較例4]
1μM HisRS(好熱菌由来)、30μM L-ヒスチジン、2mM ATP、20mM MgCl2、400mM ヒドロキシルアミン(求核剤)、200mM HEPES-KOH(pH8)を含む反応液を150μL調製し、70℃で30分間酵素反応を行った。酵素反応後、トリクロロ酢酸を終濃度4%となるように30μL添加し反応を停止した。反応停止後、遠心分離で沈殿を除去し、比較品4を調製した。
1μM HisRS(好熱菌由来)、30μM L-ヒスチジン、2mM ATP、20mM MgCl2、200mM HEPES-KOH(pH8)、及び5μM SerRS(好熱菌由来)、30μM L-セリン、2mM ATP、6mM MgCl2、200mM HEPES-KOH(pH8)を含む反応液を150μL調製し、70℃で30分間酵素反応を行った。酵素反応後、トリクロロ酢酸を終濃度4%となるように30μL添加し反応を停止した。反応停止後、遠心分離で沈殿を除去し、実施品37及び38を調製した。
比較例4及び実施例24で得られた比較品4、実施品37及び38のピロリン酸を実施例7に記載のモリブデンブルー法により測定した。その結果、図7に示すとおり、本発明の方法は添加したアミノ酸が全て反応に使用された場合に産生されると推測されるピロリン酸量の理論値より多くのピロリン酸が産生された。一方、比較品は、理論値以下だった。このことから、求核剤を使用した従来のAARSを用いた測定法では、産生されるピロリン酸の分子数はアミノ酸分子数より少ないが、本発明方法では、アミノ酸分子数より多くのピロリン酸が産生されることが示された。
[実施例26]
250mM HEPES-KOH(pH8)、31.3mM ATP、313mM MgCl2を含む反応溶液120μLに、L-セリンを終濃度50μMとなるように15μL、SerRS(大腸菌由来)を終濃度5μMとなるように15μL添加した酵素反応溶液を、10℃、30℃、40℃、45℃、50℃、60℃、70℃、80℃の各温度で30分間反応させた。反応後、トリクロロ酢酸を終濃度4%となるように30μL添加し、反応を停止した。反応停止後、遠心分離で沈殿を除去し、上清中のピロリン酸を実施例7に記載のモリブデンブルー法により測定した。その結果、図8に示すとおり、10℃から80℃の範囲でピロリン酸産生が認められ、特に30℃から60℃の範囲において良好なピロリン酸の産生が認められた。
250mM HEPES-KOH(pH8)、12.5mM ATP、125mM MgCl2を含む反応溶液120μLに、L-ヒスチジンを終濃度30μMとなるように15μL、HisRS(好熱菌由来)を終濃度5μMとなるように15μL添加した酵素反応溶液を、10℃、30℃、40℃、50℃、70℃、80℃、90℃、95℃の各温度で15分間反応させた。反応後、トリクロロ酢酸を終濃度4%となるように30μL添加し、反応を停止した。反応停止後、遠心分離で沈殿を除去し、上清中のピロリン酸を実施例7に記載のモリブデンブルー法により測定した。その結果、図8に示すとおり、10℃から95℃の範囲で良好なピロリン酸の産生が認められた。
[実施例28]
250mM HEPES-KOH(pH8)、31.3mM ATP、313mM MgCl2を含む反応溶液120μLに、L-チロシンが終濃度0μM、30μM、70μM、100μMとなるように15μL添加した各サンプルを調製後、さらに各サンプルにTyrRS(大腸菌由来)を終濃度5μMとなるように15μL添加し、50℃、30分間反応させた。反応後、トリクロロ酢酸を終濃度4%となるように30μL添加し、反応を停止した。反応停止後、遠心分離で沈殿を除去し、上清中のピロリン酸を実施例7に記載のモリブデンブルー法により測定した。その結果、図9に示すように添加したアミノ酸が全て反応に使用された場合に産生されると推測されるピロリン酸量の理論値より多くのピロリン酸が産生されていた。また、0~100μM のアミノ酸濃度範囲においてアミノ酸濃度とピロリン酸量に相関関係(R=0.97)が認められ、L-チロシンの定量が可能であることが示された。
250mM HEPES-KOH(pH8)、31.3mM ATP、313mM MgCl2を含む反応溶液120μLに、L-セリンが終濃度0μM、60μM、100μM、150μM、200μM、250μM、300μMとなるように15μL添加した各サンプルを調製後、さらに各サンプルにSerRS(好熱菌由来)を終濃度5μMとなるように15μL添加し、70℃、30分間反応させた。反応後、トリクロロ酢酸を終濃度4%となるように30μL添加し、反応を停止した。反応停止後、遠心分離で沈殿を除去し、上清中のピロリン酸を実施例7に記載のモリブデンブルー法により測定した。その結果、図9に示すように添加したアミノ酸が全て反応に使用された場合に産生されると推測されるピロリン酸量の理論値より多くのピロリン酸が産生されていた。また、0~300μMのアミノ酸濃度範囲においてアミノ酸濃度とピロリン酸量に相関関係(R=0.99)が、認められ、L-セリンの定量が可能であることが示された。
250mM HEPES-KOH(pH8)、31.3mM ATP、313mM MgCl2を含む反応溶液120μLに、L-ヒスチジンが終濃度0μM、1.0μM、3.0μM、5.0μMとなるように15μL添加した各サンプルを調製後、さらに各サンプルにHisRS(大腸菌由来)を終濃度5μMとなるように15μL添加し、50℃、30分間反応させた。反応後、トリクロロ酢酸を終濃度4%となるように30μL添加し、反応を停止した。反応停止後、遠心分離で沈殿を除去し、上清中のピロリン酸を実施例7に記載のモリブデンブルー法により測定した。その結果、図9に示すように添加したアミノ酸が全て反応に使用された場合に産生されると推測されるピロリン酸量の理論値より多くのピロリン酸が産生されていた。また、0~5μMのアミノ酸濃度範囲においてアミノ酸濃度とピロリン酸量に相関関係(R=0.99)が認められ、L-ヒスチジンの定量が可能であることが示された。
250mM HEPES-KOH(pH8)、31.3mM ATP、313mM MgCl2を含む反応溶液120μLに、L-トリプトファン終濃度0μM、1.0μM、3.0μM、5.0μMとなるように15μL添加した各サンプルを調製後、さらに各サンプルにTrpRS(好熱菌由来)を終濃度5μMとなるように15μL添加し、70℃、30分間反応させた。反応後、トリクロロ酢酸を終濃度4%となるように30μL添加し、反応を停止した。反応停止後、遠心分離で沈殿を除去し、上清中のピロリン酸を実施例7に記載のモリブデンブルー法により測定した。その結果、図9に示すように添加したアミノ酸が全て反応に使用された場合に産生されると推測されるピロリン酸量の理論値より多くのピロリン酸が産生されていた。また、0~5μMのアミノ酸濃度範囲においてアミノ酸濃度とピロリン酸量に相関関係(R=0.99)が認められ、L-トリプトファンの定量が可能であることが示された。
[実施例32]
終濃度5μM TrpRS(好熱菌由来)、0μM、15μM、20μM、40μM、50μM L-トリプトファン、10mM ATP、100mM MgCl2、1mM HEPES-KOH(pH8)を反応組成物として含む各サンプルを100μL調製し、70℃で30分間反応させた。反応後、10分室温に静置した。
終濃度5μM LysRS(好熱菌由来)、0μM、15μM、20μM、40μM、50μM L-リジン、10mM ATP、100mM MgCl2、1mM HEPES-KOH(pH8)を反応組成物として含む各サンプルを100μL調製し、実施例32と同様の処理を行った。
終濃度5μM SerRS(好熱菌由来)、0μM、20μM、50μM、60μM L-セリン、10mM ATP、100mM MgCl2、1mM HEPES-KOH(pH8)を反応組成物として含む各サンプルを100μL調製し、実施例32と同様の処理を行った。
生理活性反応測定装置(AMIS-101X、バイオエックス社製)を用いた測定を行った。累積型ISFETセンサは、参照電極内蔵AMISセンサー(AMIS-051)を使用した。AMIS-051のセンシング部A、Bに終濃度1mM HEPES-KOH(pH8)、200mM MgCl2、10mKClを含む溶液を各70μLずつ添加した。30℃で3分の予備加温を実施し、シグナルが安定した後、センシング部Aに、調製した測定対象物(実施例32~34の各サンプル)を、センシング部Bに、アミノ酸の代わりに水を添加した以外は実施例32~34の各サンプルと同じ組成の溶液を、30μL添加及び混合してシグナル変化量(センシング部Bからのシグナルと比較してのセンシング部Aのシグナル変化)を5秒ごとに250秒計測した。累積型ISFETセンサの累積回数は10回で計測した。その結果、図10に示す通り、各アミノ酸において検量線を作成でき、累積型ISFETセンサにおいてアミノ酸の定量が可能であることが示された。
[実施例36]
250mM HEPES-KOH(pH8)、31.3mM ATP、31.3mM MnCl2を含む反応溶液240μL、又は、250mM HEPES-KOH(pH8)、50mM ATP、50mM MnCl2を含む反応溶液240μL、又は、250mM HEPES-KOH(pH8)、62.5mM ATP、62.5mM MnCl2を含む反応溶液240μLを調製し、D-ヒスチジンを終濃度50μMとなるように30μL、HisRS(大腸菌由来)を終濃度5μMとなるように30μL添加し、50℃、30分間処理した。反応後、トリクロロ酢酸を終濃度4%となるように60μL添加し、反応を停止した。反応停止後、遠心分離で沈殿を除去し、実施品39~41を調製した。
250mM HEPES-KOH(pH8)、31.3mM ATP、31.3mM MnCl2を含む反応溶液240μL、又は、250mM HEPES-KOH(pH8)、50mM ATP、50mM MnCl2を含む反応溶液240μL、又は、250mM HEPES-KOH(pH8)、62.5mM ATP、62.5mM MnCl2を含む反応溶液240μL調製し、D-トリプトファンを終濃度50μMとなるように30μL、TrpRS(好熱菌由来)を終濃度5μMとなるように30μL添加し、70℃、30分間処理した。反応後、トリクロロ酢酸を終濃度4%となるように60μL添加し、反応を停止した。反応停止後、遠心分離で沈殿を除去し、実施品42~44を調製した。
[実施例38]
実施例36、37で調製した実施品39~44を、実施例7に記載のモリブデンブルー法により測定したところ、図11に示す通り、ATP、MnCl2濃度の増加とともにピロリン酸の増加が認められた。また、添加したアミノ酸が全て酵素反応に使用された場合に産生されるピロリン酸量の理論値より多くのピロリン酸が産生されていた。従って、本発明の方法によれば、試料中に含まれるアミノ酸分子数より多くのモル数のピロリン酸が産生されることが示された。
[実施例39]
250mM HEPES-KOH(pH8)、50mM ATP、50mM MnCl2を含む反応溶液120μLに、D-チロシンが終濃度0μM、3μM、5μM、10μMとなるように15μL添加した各サンプルを調製後、さらに各サンプルにTyrRS(大腸菌由来)を終濃度5μMとなるように15μL添加し、40℃、30分間反応させた。反応後、トリクロロ酢酸を終濃度4%となるように30μL添加し、反応を停止した。反応停止後、遠心分離で沈殿を除去し、上清中のピロリン酸を実施例7に記載のモリブデンブルー法により測定した。その結果、図12に示すように、添加したアミノ酸が全て反応に使用された場合に産生されると推測されるピロリン酸量の理論値より多くのピロリン酸が産生されていた。また、0~10μM のアミノ酸濃度範囲においてアミノ酸濃度とピロリン酸量に相関関係(R=0.96)が認められ、D-チロシンの定量が可能であることが示された。
250mM HEPES-KOH(pH8)、50mM ATP、50mM MnCl2を含む反応溶液120μLに、D-ヒスチジンが終濃度0μM、30μM、50μM、80μM、100μM、150μMとなるように15μL添加した各サンプルを調製後、さらに各サンプルにHisRS(大腸菌由来)を終濃度5μMとなるように15μL添加し、40℃、30分間反応させた。反応後、トリクロロ酢酸を終濃度4%となるように30μL添加し、反応を停止した。反応停止後、遠心分離で沈殿を除去し、上清中のピロリン酸を実施例7に記載のモリブデンブルー法により測定した。その結果、図12に示すように、添加したアミノ酸が全て反応に使用された場合に産生されると推測されるピロリン酸量の理論値より多くのピロリン酸が産生されていた。また、0~150μM のアミノ酸濃度範囲においてアミノ酸濃度とピロリン酸量に相関関係(R=0.99)が認められ、D-ヒスチジンの定量が可能であることが示された。
[実施例41]
各終濃度が200mM HEPES-KOH(pH8)、0.5mM L-トリプトファン、0.5mM D-トリプトファン、25μM ピリドキサールリン酸、0.8U/mL トリプトファナーゼとなるように調製し、37℃で5分間反応させた。反応後、80℃、30分で熱処理し、遠心分離で沈殿を除去した。
250mM HEPES-KOH(pH8)、50mM ATP、50mM MnCl2を
含む反応溶液240μLに、実施例41で調製したアミノ酸溶液を30μL添加した各サンプルを調製後、さらに各サンプルにTrpRS(大腸菌由来)を終濃度5μMとなるように30μL添加し、40℃、30分間反応させた。反応後、トリクロロ酢酸を終濃度4%となるように60μL添加し、反応を停止した。反応停止後、遠心分離で沈殿を除去し、実施品45を調製した。同様にして、アミノ酸として、夫々、0.5mM D-トリプトファン及び0.5mM L-トリプトファンのみを含み、トリプトファナーゼ処理をしていないアミノ酸溶液からAARS反応により産生されるピロリン酸産生量について測定するため、比較品5と比較品6を調製した。
実施例42で得られた実施品45及び比較品5、6の上清中のピロリン酸を実施例7に記載のモリブデンブルー法により測定した。その結果、図13に示す通り、実施品45と比較品5がほぼ同等のピロリン酸産生量となった。このことから、D体とL体のトリプトファン混合液中のL-トリプトファンが、酵素処理によって除去できたと考えられた。従って、L-アミノ酸を除去することで、D体とL体のアミノ酸混合液中のD-アミノ酸を測定できることが示された。
Claims (7)
- 以下の各工程を含む工程(I):
(工程I-1)二価イオン又はポリアミンの存在下、試料中のL体及び/又はD体のアミノ酸(L-AA及び/又はD-AA)、該アミノ酸に対応するアミノアシルtRNA合成酵素(AARS)、及び、アデノシン三リン酸(ATP)を反応させて、アミノアシルアデニル酸(アミノアシルAMP)とAARSから成る複合体(アミノアシルAMP-AARS複合体)を形成させる反応(反応1)を含む工程;
(工程I-2)反応1及び/又は反応3で形成されたアミノアシルAMP-AARS複合体とヌクレオチドを反応させて、該複合体からAARS及びアミノ酸(L-AA及び/又はD-AA)を遊離させる反応(反応2)を含む工程;
(工程I-3)反応2で遊離されたアミノ酸(L-AA及び/又はD-AA)及び/又はAARSを反応1において再利用することによってアミノアシルAMP-AARS複合体反応を形成させる反応(反応3)を含む工程;及び、
(工程I-4)工程I-2及び工程I-3を繰り返す工程、並びに、
工程(I)で生じた反応産生物の量を測定し、該反応産生物の測定量に基づきL体及び/又はD体のアミノ酸の量を決定することを含む工程(II)、
を含む、試料中のアミノ酸定量方法。 - イオン感応性電界効果トランジスタ、ガラス電極膜、又は、多電極電位計測計により電位変化を測定することによって、工程(I)で生じた反応産生物の量を測定する、請求項1に記載のアミノ酸定量方法。
- 吸光度法により吸光度変化を測定することによって、工程(I)で生じた反応産生物の量を測定する、請求項1に記載のアミノ酸定量方法。
- 工程(I)で生じる反応産生物として、ピロリン酸又は水素イオンの少なくとも何れか1つを測定する、請求項1~3のいずれか一項に記載のアミノ酸定量方法。
- 工程(I)で生じた反応産生物のモル数が試料中のアミノ酸のモル数より多いことを特徴とする、請求項1~4のいずれか一項に記載のアミノ酸定量方法。
- 前処理として、試料中のL体又はD体のアミノ酸の何れか一方を除去することを特徴とする、請求項1~5のいずれか一項に記載のアミノ酸定量方法。
- 請求項1~6のいずれか一項に記載のアミノ酸定量方法を実施するためのアミノ酸定量用キットであって、ATP、ヌクレオチド及び該アミノ酸に対応するAARSを含む、前記アミノ酸定量用キット。
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WO2019198623A1 (ja) * | 2018-04-12 | 2019-10-17 | 池田食研株式会社 | アミノ酸定量方法及びアミノ酸定量用キット |
JPWO2019198623A1 (ja) * | 2018-04-12 | 2021-04-15 | 池田食研株式会社 | アミノ酸定量方法及びアミノ酸定量用キット |
JP7333547B2 (ja) | 2018-04-12 | 2023-08-25 | 池田食研株式会社 | アミノ酸定量方法及びアミノ酸定量用キット |
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CN109073590B (zh) | 2021-10-29 |
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