JP2007064950A - Method and system for analysis of sulfation glycolipid - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide method and system for achieving MALDI TOF MS-based high-sensitive analysis of sulfation glycolipid, namely, minor constituent contained in micro biological sample, by very simply making pretreatment of the intended constituent, analyzing micro sample in a short time, and easily identifying isomer of the sulfation glycolipid. <P>SOLUTION: This method is to analyze sulfation glycolipid, characterized by comprising a process to analyze purified fraction with MALDI TOF MS by allowing the micro biological sample to pass three-dimensional network shaped through-hole provided on monolithic structure, a process to lysogenize the above purified fraction, and a process to identify sulfation glycolipid based on analysis results of the process to analyze this lysogenized fraction with MALDI TOF MS and the above two MALDI TOF MS-based processes. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to a method for identifying an isomer of a sulfated glycolipid from a trace amount of biological sample and an analysis method therefor. In particular, it is a method for distinguishing and analyzing complex isomers of sulfated glycolipids that have potential to become novel markers such as cancer and arteriosclerosis. Furthermore, the present invention relates to a microanalysis method incorporating these methods.

  Sulfated glycolipid (sulfatide) is reported to increase in cancer diseases such as liver cancer, kidney cancer, colon cancer, ovarian cancer, uterine cancer, lung cancer, etc., and may be a marker for the disease Was suggested. Sulfatides are made up of various combinations of sulfated sugar and lipid moieties, but more recently, those with a particular lipid moiety are especially important for disease prognosis. It has been suggested that there is. Conventionally, a method using a specific antibody has been used for microanalysis of sulfatide, but it has been reported that there is a problem in specificity. In addition, in the technique using an antibody, only information on the sugar chain portion can be obtained, and information on a lipid portion which has recently been important cannot be obtained. As a method for solving this problem, a chromatographic column in which sulfatide is extracted and packed, and a thin layer chromatogram in which particles are applied to a glass plate are purified and analyzed by a mass spectrometer (Non-Patent Documents). However, these means are cumbersome, require various special techniques and labor time, and have been problematic for use in rapid analysis of biological samples.

  In recent years, in this so-called treatment, a cartridge column is filled with a particle filler instead of the conventional method that requires complicated and special equipment / technology such as column chromatography packed with large particles and thin layer chromatography. A method called a solid-phase extraction method has been established (see Non-Patent Document 2). As a result, the simplicity and rapidity of the pretreatment process have been remarkably increased, but there are still many problems in processing a small amount and a small amount of components.

  The solid-phase extraction method is a method of separation and purification by selectively adsorbing and holding only the target component from a sample containing complex components. Basically, it is a theoretical development of high-performance liquid chromatography. This is a pre-analysis method devised in Japan. In general, only a target component is adsorbed and held on a solid-phase extraction agent from a sample containing a plurality of components, and then only the target component is obtained by washing and elution operations. Thereby, it is possible to easily obtain the effects of “rough extraction”, “concentration”, and “cleanup” of the target component. The solid phase extraction method is useful for simplifying the process and shortening the labor time.

As the solid phase extraction agent, there are various forms such as those using particles of 10 μm to 100 μm, and those in which the particles are fixed with a fiber to form a filter. However, in these methods, in order to prevent the particles used as the solid phase extraction agent from deviating into the eluate, a filter that is not involved in the separation is disposed at the entrance / exit.
The particle deviation prevention method using a filter cannot be used at a high flow rate because particle detachment from the membrane or outflow of the particle through the filter is observed with a rapid pressure change. For this reason, it is difficult to shorten the pretreatment time of the trace component in the living body, which is the purpose.
As described above, the solution used during processing and the target component during elution often remain inside the filter. In particular, the residual eluate during extraction of a trace amount of the target component results in a significant loss of the target component. To solve this, it is possible to add enough solution volume to elute, but increasing the eluate means diluting the sample, which leads to a decrease in sensitivity in later detection operations. For this reason, it is not suitable for purifying trace components in the living body, which is the purpose.

  As the simplest method for avoiding such a phenomenon, it is conceivable to reduce the size of the container (cartridge) filled with the solid phase extraction agent. However, when the conventional solid phase extraction agent is filled, the container volume can be reduced. Along with this, the filling amount must also be reduced, and it becomes difficult to exhibit sufficient adsorption / holding ability. In these forms, the resistance to fluid flow increases with downsizing, and it becomes difficult to perform fluid flow by a method such as suction and centrifugation, and cannot be used practically.

  It is impossible to apply a pressure of 1Mpa or more to a resin cartridge used for particle-type cartridge type solid phase extraction, and high pressure packing like an HPLC column is not possible. It is difficult to get. As a result, variations in the filling state are likely to occur, which leads to variations in liquid flow resistance and adsorption / holding performance, and causes a decrease in the reproducibility of the experimental results. Even in the membrane type solid-phase extraction method, the particle space changes due to pressure fluctuation, and as a result, the reproducibility is similarly lowered.

  In particular, in an analysis aimed at identifying a component using a matrix-assisted laser desorption / ionization time-of-flight mass spectrometer (MALDI / TOF / MS) (see, for example, Patent Document 1), The components are identified for the first time by performing the process of `` pre-processing by extraction method and mass spectrometry '' multiple times and comparing the results, so the decrease in reproducibility in each solid phase extraction is It causes a decrease in accuracy.

  On the other hand, in the solid-phase extraction process using particle-packed or membrane-type solid-phase extraction agents, the solution is reciprocated to the solid-phase extraction agent by suction and discharge in order to enhance adsorption and retention capacity and prevent dilution during elution. In this method, a turbulent flow is generated between the particles of the solid phase extractant. Since the generation of turbulent flow significantly disturbs the liquid flow state, it is not possible to improve the processing capacity of solid phase extraction. Therefore, in the case of a particle-filled type or a membrane type solid-phase extraction agent, there is only a method for improving accuracy by flowing a liquid flowing inside in a constant direction at a constant flow rate. In other words, in a conventional solid-phase extraction, a dilution system in which elution is performed a plurality of times by passing in a certain direction in order to completely elute the adsorbed target component. Become. For this reason, it is necessary to further concentrate a large amount of the eluate obtained after purification with trace components. As a result, the trace amount of remaining contaminant components eluted simultaneously with the target component and the trace amount of impurity component contained in the eluate itself are concentrated at the same time, resulting in a decrease in detection sensitivity and an increase in noise level. It is not suitable for pretreatment of components contained in trace amounts in the living body.

Furthermore, in the treatment of sulfated glycolipids, conventionally known addition of salts for enhancing the solvent concentration effect cannot be used because it causes decomposition of the substance to be analyzed itself. Therefore, it is indispensable to concentrate under mild conditions, and pretreatment time is required.
In addition, if the amount of the pretreated elution solution increases, when further processing is performed on the eluted components, it is necessary to further concentrate, and the above phenomenon occurs, so that it cannot be practically used.

  As described above, in the conventional method, due to various problems in the pretreatment stage, a biological sample (tissue, cell, etc.) of about 0.5 to 1.0 g is required as a starting material for analysis. For this reason, it has been impossible to process biological samples such as tubule cells that originally exist in minute amounts.

Special table 2005-521892 Matrix-assisted laser desorption / ionization mass spectrometry of sphingo and glycosphingo-lipidsDavid J. HarveyJournal of Mass SpectrometryVolume 30, Issue 9, 1995 Pages 1311-1324 Extraction and analysis of multiple sphingolipids from a single sampleTaketomi T, Sugiyama E. Methods Enzymol. Volume 312, 2000. Pages 80-101

  In order to identify the structure of sulfated glycolipids, which are trace components contained in a trace amount of biological samples, through a pretreatment process using MALDI, TOF, and MS, It is necessary to elute the target component without diluting it, and to perform lyso-formation treatment that separates fatty acids from sulfated glycolipids for identification, and after lyso-formation treatment, it is necessary to perform pretreatment to supply to MALDI / TOF / MS is there.

  In this pretreatment process, conventional column chromatography or solid phase using particles can only flow sample solution and eluate in a certain direction. Therefore, in order to obtain sufficient pretreatment results, multiple passes are required. A liquid is required, and the amount of liquid increases and the target component is diluted. Therefore, a process for removing a large amount of solvent is required. In sulfated glycolipids that are contained only in trace amounts in the living body, impurities remaining in trace amounts after decomposition during solvent removal and pretreatment are also concentrated at the same time.

  Therefore, a means for removing impurities while concentrating only the target component in a certain volume is indispensable. Conventionally, this method includes recycling fractionation through a column several times, but the apparatus is expensive and takes several hours.

  If a separation medium having separation ability and capable of repeatedly passing liquid can be made in a small field, trace components can be purified efficiently. Small places include syringe needles and pipettes. There is a demand for a separation body to be attached that is a solid body that does not change in volume even when a liquid is passed through it, and that has a sufficient holding ability when the liquid is flowed. It is necessary that chemical species involved in separation be freely bonded to the surface of the separator.

  In addition, the present invention performs high-sensitivity analysis by MALDI / TOF / MS through a simplified pretreatment process of sulfated glycolipids, which are trace components contained in trace biological samples such as rat tubular cells. The purpose is to develop and provide a method for identifying isomers of sulfated glycolipids.

  MALDI / TOF / MS can be used in the clinical field in the future because it can analyze a small amount of sample in a short time even with a large number of samples. Met. In addition, the lipid part of sulfated glycolipid consists of a part called fatty acid and sphingosine, and it is very complicated and the existence of various isomers is assumed. Therefore, a method for clarifying this part is necessary.

Therefore, the present invention proposes the following configuration.
It consists of the process of selectively purifying only the sulfated glycolipid component from a small amount of biological sample, and further the step of lysing the purified sulfated glycolipid component and removing impurities generated by lyso-formation. And a method for analyzing sulfated glycolipid.

  Further, in the above method, in the selective purification step and the impurity removal step, a method for analyzing sulfated glycolipids using a monolith structure having a three-dimensional network structure through-hole in one or both steps .

  Furthermore, in the method described above, a method for analyzing sulfated glycolipid, wherein the detection step is performed by MALDI / TOF / MS in the selective purification step and the detection step after removing the impurities.

  Furthermore, in the above method, a sulfated glycolipid analysis method for identifying sulfated glycolipids in a small amount of living body by comparing the analysis results of MALDI, TOF, and MS obtained in each step.

  A monolith structure for analysis of sulfated glycolipids, wherein the through-holes of the three-dimensional network structure are 1 μm to 100 μm.

  A monolith structure for analysis of sulfated glycolipids, wherein the main component of the skeleton of the monolith structure having through-holes having a three-dimensional network structure is Si.

  Also, a monolith structure in which a sulfated glycolipid and a lyso-formation component, which is a constituent component thereof, can be purified by reverse phase partitioning by chemically bonding an alkyl chain to the monolith structure.

  In addition, a solid phase extraction device made of a monolith structure is detachably installed in the liquid contact portion of the suction and discharge mechanism, and the liquid contact portion is provided movably between the carrier of the solution and the reagent. An apparatus for analyzing sulfated glycolipids, wherein adsorption, washing, and elution processes for the target component of the product can be freely selected.

  The present invention uses a solid-phase extraction agent having a structure that does not use particles in the process of extraction and purification of sulfated glycolipids, thereby performing solid-phase extraction with high efficiency and preventing residual particles after purification. Demineralization operation, which is an ionization auxiliary process, that makes it possible to significantly simplify pretreatment processes such as particle removal and prevent sample loss, while facilitating ionization, which is extremely important in MALDI, TOF, and MS. Can be easily and conveniently performed. In addition, we succeeded in lyso-formation, a process that separates fatty acids from sulfated glycolipids, and by combining these methods, identification of isomers (molecular species) of sulfated glycolipids is simple, rapid, and in minute amounts. Made it possible.

  By using this method, the conventional method required a biological sample (tissue, cell) of about 0.5 to 1.0 g as an analysis starting material, and using a biological sample of only about 10 to 40 mg. It has become possible to perform the measurement without lowering the detection sensitivity.

In order to perform desalting and purification of sulfated glycolipids in a small amount of biological sample using solid phase extraction without dilution, (1) high hydrophobic interaction, (2) large surface area, and good fluid flow I need sex.
Hydrophobic interaction: An interaction in which non-polar groups with low affinity to water molecules try to gather together in an aqueous solution.
In the present invention, lipids extracted by applying various treatments from biological samples include, in addition to the target lipids (non-polar substances), polar substances contained in the original sample and extractions. A large amount of salts (polar substances) added to the process are present. In order to purify only lipids from these mixtures, the sample solution is brought into contact with a solid phase extraction agent modified with an alkyl chain (for example, okdadecyl group), which is a nonpolar substance similar to lipids, After the lipids are adsorbed to the alkyl chain (solid phase), non-polar substances such as salts are washed away, and the adsorbed target components (lipids) are eluted.

When purifying a very small amount of substance based on such a principle, the solid phase that modifies the alkyl group needs to have a large surface area to reliably adsorb a small amount of lipids. However, when a conventionally known particulate solid phase is used, the only way to increase the surface area is to reduce the particle diameter or use a large amount of particles. However, in these methods, there are problems such as a liquid passage failure due to an increase in liquid flow resistance and a remaining solution due to an increase in solid phase volume.
Therefore, in the present invention, “a single three-dimensional network having a through-hole having a three-dimensional network structure” is a structure capable of minimizing an increase in liquid flow resistance with an increase in surface area and an increase in solid phase volume. A monolith structure having “structure” and having “substance characteristics that can easily modify a non-polar functional group such as an alkyl chain” was used.
Furthermore, since this monolith structure has high strength, it is possible to adopt a method of repeating the process of reciprocating the liquid. By using this method, even when the amount of the solution containing the target substance for solid phase extraction is small, the number of times of contact between the solid phase extraction agent and the solution increases, so that it can be purified without being diluted.

Specifically, 1 μm to 100 μm is preferable as a through-pore that is a through hole through which a liquid flows, but it varies depending on a method and an apparatus to be used.
Basically, the smaller the through-pore diameter, the larger the contact area, but the liquid flow resistance when flowing liquid also increases. When a commercially available manual pipettor is used, a through-pore of about 10 μm to 30 μm is desired from the liquid resistance in and out. Since the automated device according to this purpose can use a pump or the like, it can be used even when a higher resistance to flow is generated. Therefore, the through-pore is reduced to about 3 μm to 15 μm and the wetted area is reduced. Can be increased.

  A monolith structure having a through pore diameter of 10 μm to 30 μm has the same surface area as a particle diameter of 20 μm to 30 μm when converted as the particle diameter of the particulate solid phase extractant. Since the particle diameter currently used as general solid phase extractant particles is 40 μm to 60 μm, the particle diameter is halved. Since the relationship between the particle diameter and the resolution is the inverse of the square, the solid phase extractant using a monolith structure with a through pore of 10 μm to 30 μm is a solid phase using particles of 40 μm to 60 μm. It has about 4 times the separation ability compared to the extractant. In the present invention, when a lyso form of a sulfated glycolipid is purified by solid phase extraction, the nonpolar substances contained include fatty acids cleaved from the sulfated glycolipid in addition to the lysosulfated glycolipid. . From here, not only salts but also other mixed polar low-molecular contaminants are removed, and the high resolution of the monolith structure is also effective in selecting and separating only the lyso form.

  As mesopores on the skeleton surface of the monolith structure, non-porous to 1000 angstroms having a large diameter of 50 angstroms or less can be applied. Pore is suitable.

  In addition, since the sample solution is reciprocated, the monolith structure is required to have a high pressure resistance type monolith structure with as little change in volume of the solid phase extractant as possible. In a solid-phase extraction agent using a polymer monolith or a membrane, volume change is likely to occur during suction and discharge operations. Therefore, a monolith structure made of a metal oxide having a withstand voltage is useful.

In particular, in the case of biological sample components, non-objects may be adsorbed depending on the raw material forming the monolith structure, and those with a proven Si skeleton such as a solid phase are recommended.
That is, etching of baked glass with monolith, silicon hydroxide, silicate, etc. by sol-gel synthesis performed after tetraethoxysilane, tetramethoxysilane, methyltrimethoxysilane, methyltriethoxysilane, etc. alone or mixed. A monolith structure made of

  In addition, as a chemical species such as an alkyl chain chemically modified on the surface of the silica monolith structure in order to adsorb the sulfated glycolipid and the lyso form, which is a constituent component thereof, octadecyltrimethylchlorosilane, which has been conventionally used for fillers, Octadecyldimethyldichlorosilane, octadecyltrichlorosilane, octadecyltrimethoxysilane, octadecylmethyldimethoxysilane, octyltrimethylchlorosilane, octyldimethyldichlorosilane, octyltrichlorosilane, octyltrimethoxysilane, octylmethyldimethoxysilane, methyltrimethylchlorosilane, methyldimethyldichlorosilane Silane agents having an alkyl chain such as methyltrichlorosilane, methyltrimethoxysilane, and methylmethyldimethoxysilane can be used. It is also effective to use a monolith structure in which polar groups are introduced between them to improve the compatibility with the liquid and irreversible adsorption is suppressed by applying an end cap.

The following embodiments of the present invention will be described.
For example, sulfatide SM4s (d18: 1-C24: 0h) (FIG. 2A), which is a kind of sulfated glycolipid, and sulfatide SM4s (t18: 0-C24: 1) (FIG. 2B) have a double bond position and Despite the different positions of hydroxyl modification, the composition formulas are both C ₄₈ H ₉₃ NO ₁₂ S, the molecular weight calculated by monoisotopic is 907.6, measured and detected in the negative mode of MALDI / TOF / MS The deprotonated molecule m / z is exactly the same as 906.6. In other words, such molecular species cannot be distinguished by analyzing a sulfated glycolipid extracted and purified from the living body as it is using a mass spectrometer.
However, by chemically treating this sulfated glycolipid with the same molecular weight, separating the fatty acid moiety and lysing it, the molecular weight differs due to the difference in double bond and hydroxylation modification, and the molecular species is identified. It is possible.

That is, lyso-formation of SM4s (d18: 1-C24: 0h, m / z = 906.6) results in lyso-SM4s (d18: 1) (FIG. 2C), and m / z is 540.3. Become. On the other hand, SM4s (t18: 0-C24: 1, m / z = 906.6) becomes lyso-SM4s (t18: 0) by lyso-formation treatment (FIG. 2D), and m / z is 558.3. Become. Thereby, the structure (composition) of the lyso form, which is a sulfated glycolipid excluding fatty acids, is determined, and the molecular weight and composition of the divided fatty acids are determined by subtracting the molecular weight of the lyso form from the molecular weight before decomposition.
Thus, by comparing the mass spectrometry result of the sulfated glycolipid as extracted from the biological sample and the mass spectrometry result of the chemical treatment, the isomer (molecule) of the sulfated glycolipid can be accurately determined. It is possible to determine.
When analyzing trace components such as sulfated glycolipids using MALDI / TOF / MS according to the above method, the sensitivity is the desalting operation (removal of difficult-ionized salts), which is the pretreatment of MALDI / TOF / MS analysis. It depends on how. That is, a process for facilitating ionization is very important.

    By using a monolith structure different from a conventional solid phase as a pretreatment agent, a biological sample can be purified by suction and discharge, and a trace amount of sulfated glycolipid can be detected by MALDI / TOF / MS.

The present invention can purify a target component without dilution by using a monolith structure, which is a single structure having a through-hole through which a three-dimensional network-like liquid flows, as a pretreatment agent for sulfated glycolipid analysis. , Enabling secondary processing for identification.
In the case of the sulfated glycolipid in the present invention, separation between isomers is important, and silica gel having a silanol group that can easily introduce a chemical bonding group is effective.

If an example of this invention is demonstrated in order of a process, a sulfated glycolipid will be identified through the following processes.
(1) Separation of total lipid fraction from trace biological samples (biological tissue, blood, body fluid, etc.) (2) Separation of fraction rich in sulfated glycolipid from total lipid fraction (3) Sulfated glycolipid Selective purification of fractions (preparation of MALDI / TOF / MS analysis)
(4) Mass analysis of sulfated glycolipid fraction by MALDI / TOF / MS (5) Degradation of sulfated glycolipid fraction into lysosulfated glycolipid by chemical treatment of (4) (6) Lyso Removal of impurities such as sulfated glycolipid salts (pretreatment for MALDI / TOF / MS analysis)
(7) Mass spectrometry of lysosulfated glycolipids by MALDI / TOF / MS (8) Identification of sulfated glycolipids from mass spectrometry results of (4) and (7)

In the steps (1) and (2), the sulfated glycolipid, which is the analysis target component, is extracted from the biological sample by liquid layer separation.
This method is used in the pretreatment of the MALDI / TOF / MS analysis in the steps (3) and (6). The treatment agent used in this method is mainly capable of desalting the weakly ionized salts contained in the extraction process of sulfated glycolipids, minimizing dilution during the treatment process of trace amounts of target components, and concentrating. What has an effect and can be operated quickly and easily is desirable. As a material satisfying this condition, for example, a porous body using an inorganic material such as silica gel, and preferably a double pore having a through hole of 1 μm to 100 μm and having a nanometer size pore (mesopore) It is a monolith structure formed into a structure, and a structure in which an alkyl chain is further modified by a chemical bond is used. In addition, a pretreatment material for sulfated glycolipid analysis in which these monolith structures were fitted in a pipette tip for a general-purpose pipettor was used.

In the above steps (4) and (7), mass spectrometry of sulfated glycolipids is performed in the negative mode of MALDI / TOF / MS. The result obtained in the process of (4) is a mass analysis result of all sulfated glycolipids, and it is impossible to distinguish isomers having the same molecular weight. The result obtained in the process of (7) is the result of mass spectrometry of the lyso form, which is a component of sulfated glycolipid.
In the step (8), the fatty acid structure is identified from the result obtained in (4) based on the information of the lyso form obtained in (7).

  When the present invention is actually used, partial automation or even full automation is possible by using the following mechanism and apparatus.

  For analysis of sulfated glycolipids using a monolith structure, if the chip, tube, etc. that come into contact with the liquid that is the object to be processed are removable and have a mechanism that can be connected to and sucked and discharged It is possible to form a pretreatment device.

  A pretreatment agent for sulfated glycolipid analysis made of a monolith structure is fitted or fused to a detachable wetted part (generally called a tip or a needle), and this member is placed in a sample solution according to the purpose. By performing suction and discharge in the state of being inserted into the column, it is possible to perform steps of adsorption (holding), washing, and elution of the target component to the pretreatment agent for sulfated glycolipid analysis.

  Various mechanisms can be considered for this suction and discharge. However, because of the nature of the monolith structure, strong suction and discharge performance is not required. An air displacement type pipetting method using a syringe having a structure is sufficient. In this method, by pulling out the plunger of the syringe, the inside of the syringe is made negative pressure, and the liquid is sucked by the pressure difference. Next, by pushing the plunger, the inside of the syringe is brought to a positive pressure, and the sucked liquid is discharged. In this method, suction and discharge are performed.

  Desirably, in addition to the above-described tip attachment / detachment / exchange mechanism, a dispensing probe channel function capable of sucking and discharging an arbitrary amount of liquid, a container carrier capable of preparing a plurality of solutions in advance, Has the above-mentioned wetted part and the part responsible for suction and discharge at the tip of the drive device that can freely move between the reagent carriers, and can move between each reagent and perform the suction, discharge, transfer, etc. of the reagent solution Therefore, most of the analysis method shown in Example 1 can be performed by the apparatus.

  In addition, since the processing capacity in such an apparatus depends on the number of mechanisms that perform suction and ejection, a drive mechanism that operates more mechanisms simultaneously increases the simultaneous processing capacity and increases the per-sample. The processing time can be shortened.

  In the case of conventional particle-packed solid-phase extraction, it has been impossible to place a solid-phase extraction agent in a portion where suction and discharge are performed due to a method of use by passing liquid in a certain direction. For this reason, the reagent solution was dropped from the upper part of the solid-phase extractor and the liquid was passed by suction from the lower part of the solid-phase extractor. Therefore, as a device, a mechanism for sucking from the lower part of the solid-phase extractant is required in addition to a mechanism for sucking and discharging. In addition, a device such as a vacuum pump is essential for this suction. In the present invention, solid-phase extraction can be performed with an extremely simple apparatus as compared with these apparatuses.

  As a pretreatment agent for sulfated glycolipid analysis, an octadecyl group is chemically modified on the surface of silica monolith and extracted from a small amount of biological sample using a pretreatment material for sulfated glycolipid analysis placed in a pipette tip. Purification of the sulfated glycolipid fraction and purification of the lysosulfated glycolipid fraction obtained by appropriately treating the sulfated glycolipid, and the respective MALDI / TOF / MS analysis were performed (FIG. 1). . In addition, the pretreatment material for sulfated glycolipid analysis is attached to a general-purpose pipettor, and the operation of repeating suction and discharge (pipetting operation) allows the solution to be passed through the pretreatment agent for sulfated glycolipid analysis. Is possible.

  Methods: Rats (obtained from F344 Charles River) were sacrificed under ether anesthesia, the kidneys were removed and the renal pelvis portions were removed, and then the tubule cells and glomeruli were separated from the kidneys using the sieving method. Put 10 to 40 milligrams of tubule cells thus obtained in a wet weight into a polypropylene tube, add 1.2 ml of a mixture of hexane and 2-propanol in a ratio of 3 to 2, and homogenize well, centrifuge, Remove the liquid, add hexane, 2-propanol, and 60: 40: 3 (hereinafter referred to as A solution) to the remaining residue, add sonication, and homogenize well, then centrifuge. The supernatant was taken and combined with the previously saved supernatant to obtain a total lipid fraction.

  Using a centrifugal evaporator (CVE-2000 manufactured by Tokyo Science Equipment Co., Ltd.), the organic solvent was removed, and 1 ml of solution A was added again, and then 30 microliters of 5N sodium hydroxide dissolved in methanol was added and stirred vigorously immediately. And then centrifuged. It is divided into an upper layer and a pelleted lower layer. The upper layer is carefully removed, the lower layer is carefully neutralized with acetic acid, and evaporated to dryness with a centrifugal evaporator. For the analysis of sulfated glycolipids, add 200-300 μl of the mixture and mix well with 200 μl of methanol, 200 μl of distilled water, and finally 200 μl of 200 μl of methanol-distilled water 2-8. The pretreatment material was passed through three times.

  Thereafter, this pretreatment material for sulfated glycolipid analysis was washed with 200 to 300 μl of distilled water, and then 200 to 300 μl of methanol was passed through this pretreatment material for sulfated glycolipid analysis and collected with a centrifugal evaporator. Methanol was removed to obtain a sulfated glycolipid fraction.

A solution (hereinafter referred to as solution B) prepared by mixing acetonitrile saturated with alpha-cyano-4-hydroxycinamic acid and 0.1% trifluoroacetic acid on a one-to-one basis was prepared. 1 to 2 μl of the previously obtained sulfated glycolipid fraction 1 dissolved in solution A and mixed with 1 volume of solution B is immediately placed on a sample plate dedicated to the measuring instrument. TOF / MS analysis was performed. The model used was a VoygerEliteXL manufactured by Persert Biosystems, and a 337 nm nitrogen laser was used for ionization and analysis was performed in a negative mode.
The results are shown in FIG. As shown in FIG. 3, sulfatide SM4 _S (FIG. 3A), SM3 (FIG. 3B), and SM2 (FIG. 3C) are detected using only a part of the extracted / purified product from a small amount of biological sample of 10 to 40 mg. Was made.

Further, a part of the sulfated glycolipid fraction was dissolved in 300 μl of 0.1N sodium hydroxide dissolved in methanol, placed in a Pyrex (registered trademark) glass tube, sealed, and heated at 160 ° C. for 10 minutes. . After cooling, add 10 μl of 7N hydrochloric acid, 10 μl of distilled water and 530 μl of hexane, and after stirring well, remove the upper layer, centrifuge and evaporate the lower layer, remove the organic solvent, and add 200 μl of a mixture of methanol and distilled water 4 to 6. Mix well and pass through 200 μl of methanol, 200 μl of distilled water, and finally 200 μl of a mixture of 200 μl of methanol / distilled water 4/6 to the pretreated material for sulfated glycolipid analysis that has been equilibrated three times. did. Thereafter, this pretreatment material for sulfated glycolipid analysis was washed with 200 to 300 μl of distilled water, and then 200 to 300 μl of methanol was passed through this pretreatment material for sulfated glycolipid analysis and collected with a centrifugal evaporator. Methanol was removed to obtain a sulfated lysoglycolipid fraction. This was dissolved in solution A, the same amount of solution B was mixed, and lysosulfated glycolipid was also subjected to MALDI / TOF / MS analysis as described above.
The results are shown in FIG. As shown in FIG. 4, lysosulfatide SM4 _S (FIG. 4A), SM3 (FIG. 4B), and SM2 (FIG. 4C) could be detected.

Structure diagram SM4 _S : sulfated galactosylceramide (FIG. 5A)
SM3: sulfated lactosylceramide (FIG. 5B)
SM2: sulfated gangliosylceramide (FIG. 5C)
As strong peaks, 878.6, 892.6, 906.6 are shown for SM4 _S (FIG. 3A), 1042.7, 1056.7, 1070.7 are shown for SM3 (FIG. 3B), and 1245. 8, 1259.8 and 1273.8 were detected (FIG. 3C), respectively. Within each group, m / z differs by 14.0 each, which is equivalent to one unit of methylene (—CH ₂ —).
In addition, SM0.6 _S has 850.6, 862.6, 890.6, 924.6 (FIG. 3A), and SM3 has 996.6, 1014.6, 1024.6, 1052.7, 1084 as small peaks. .7 (FIG. 3B) and 1199.7, 1217.7, 1227.7, 1255.8, 1271.8, and 1287.8 were detected in SM2 (FIG. 3C), respectively.

If SM4s and SM3 have the same ceramide, the difference in molecular weight is Hex-H ₂ O (molecular weight obtained by subtracting the molecular weight of H ₂ O from Hexosc), which is 162.1 (FIG. 5A, Compare the structure of B). When comparing the 878.6 peak of SM4s (FIG. 3A) and the 1042.7 peak of SM3 (FIG. 3B), the molecular weight is 164.1 different. This suggests that the structures of both ceramides are different, and the ceramide possessed by 878.6 (SM4s) has one more double bond than the ceramide possessed by 1042.7 (SM3). ing.
Such a relationship is also seen between 892.6 (SM4s) and 1056.7 (SM3), 906.6 (SM4s) and 1070.7 (SM3).

On the other hand, if SM3 and SM2 have the same ceramide, the difference in molecular weight is 203.1, which is one unit of HexNAc-H ₂ O (molecular weight obtained by subtracting the molecular weight of H ₂ O from N-acetyl-hexamine) (FIG. Comparison of the structures of 5B and C). When comparing the peak of SM3 1042.7 (Fig. 3B) and the peak of SM2 1245.8 (Fig. 3C), the molecular weight difference was 203.1, indicating that it has the same ceramide. Yes. Similar relationships can be seen between 1056.7 (SM3) and 1259.8 (SM2), 1070.7 (SM3) and 1273.8 (SM2).

Thus, the major peaks of the three sulfatides (SM4s, SM3, SM2) suggest that SM4s has a unique ceramide, while SM3, SM2 have the same ceramide.
On the other hand, comparing each minor peak, the difference between 890.6 (SM4s) and 1052.7 (SM2) is 162.1, and the difference between 1052.7 (SM3) and 1255.8 (SM2) is 203. .1. This indicates that sulfatide has the same ceramide. A similar relationship can also be seen in 862.6 (SM4s) /1024.6 (SM3) /1227.7 (SM2).

More detailed information was obtained by analyzing the lyso form (FIG. 4). In SM4s, 540.3 was detected as a major peak in the analysis of lyso SM4s. This indicates d18: 1. The minor peaks are 538.3 (d18: 2), 558.3 (t18: 0), 568.3 (d20: 1), and 570.3 (d20: 0) (FIG. 4A).
Compared with the SM4s analysis results (FIG. 3A), the major peaks of FIG. 3A, 878.6, 892.6, and 906.6, are d18: 1-C22: 0h, d18: 1-C23: 0h, d18, respectively. : 1-C24: 0h. The minor peaks of the SM4s analysis results, 850.6, 862.6, and 924.6, are d18: 1-C20: 0h, d18: 1-C22: 0, t18: 0-C24: 0h.

  In the analysis of the SM3 and SM2 lysates (FIG. 4B, C), three peaks were detected in a similar pattern. In SM3, they are 702.3, 720.3, and 732.4, and in SM2, they are 905.4, 823.4, and 935.5. This indicates that lyso SM3 and lyso SM2 mainly have t18: 0 and d18: 1 and d20: 0 together with the detection intensity of mass spectrometry.

For example, SM3 having d18: 1 and d20: 0 as constituent components are both represented by the same chemical formula C ₅₂ H ₁₀₁ NO ₁₇ S. The SM3 major peaks 1042.7, 1056.7, 1070.7 and SM2 major peaks 1245.8, 1259.8, 1273.8 are probably t18: 0-C22: 0, t18: 0- C23: 0, t18: 0-C24: 0, and possibly a small amount of d20: 0-C20: 0h, d20: 0-C21: 0h, d20: 0-C22: 0h It may be a component. This is suggested by the results of analysis of lyso SM3 and lyso SM2 that t18: 0 is a major sphingosine and d20: 0 is a minor sphingosine (FIGS. 4B and 4C).

Therefore, sulfatide SM4s mainly consists of sphingosine called 4-sphingenin (d18: 1) and a fatty acid that has undergone hydroxylation with carbon numbers of 22, 23, and 24, and sulfatides SM2 and SM3 are mainly phytophylls. It was found to be composed of sphingosine called sphingosine (t18: 0) and a fatty acid having carbon numbers of 22, 23 and 24 and not subject to hydroxylation. It was also found that in SM4s, SM3, and SM2, there is a sphingosine of 20 dihydrosphingosine, which has not been known so far in sulfatide.
Similarly, similar results were obtained when the conventional solid phase was used and a sample of 0.5 to 1 g was used. However, at a concentration of 1/50, SM3 was completely different in MALDI / TOF / MS. It was not detected. Further, although SM4s and SM2 were detectable, the detection intensity was lower than that in the case of using a monolith structure, and SM2 was particularly difficult to identify.
By using this method, a trace amount of sulfatide could be detected, and identification from the structure became possible.

The pretreatment material for sulfated glycolipid analysis used in this example is obtained by fusing a monolith structure to a general-purpose pipettor pipette tip. The fused monolith structure has a skeleton made of silica gel, and an octadecyl group is chemically bonded to the skeleton. In the monolith structure, this skeleton is connected in a three-dimensional network shape to form an integral structure. Between each skeleton, there is a through-hole related to liquid passage having a diameter of 10 to 20 μm that penetrates from one end to the other end. The skeleton itself has pores of about 20 nm. The outer shape of the structure is approximately 3.2 mm in diameter, approximately 1.0 mm in thickness (volume approximately 8 μl (mm ³ )), and approximately 2 mg in weight, which is smaller than conventional solid-phase extraction. However, the surface area is about 0.4 mm ² (200 mm ² / g × 2 mg), and when an amount of load is calculated using Angiotensin II, a large amount of sample of 100 μg can be processed.

Automation was performed using a Microlab (registered trademark) STAR manufactured by Hamilton which is a fully automatic dispensing system.
This fully automatic dispensing system has a dedicated tip detachment function, multiple arms with dispensing probe channels that can suck and discharge any liquid volume, and a container carrier that can mount containers of various shapes. By creating a sequence program, it is possible to automate various processes such as dispensing, transferring, and mixing of solutions.
For this purpose, a monolith structure in which an octadecyl group was modified was fused to a dedicated chip and used.

The process for obtaining a sulfated glycolipid fraction is shown below.
Reagent used Methanol: Distilled water = 2: 8 (hereinafter referred to as “C solution”)
Prepare methanol distilled water in advance in the carrier.

First, the same method as in Example 1 was used for separation of glomeruli from rats, separation of the total lipid fraction, and treatment of the total lipid fraction to obtain a pellet-like substance and evaporate to dryness.
The evaporated and dried pellets were set in a sample rack of an automatic dispensing system Microlab (registered trademark) STAR.

In the following steps, processing steps were executed by a sequence program.
1. Attach High volume Tips (for 5 μl to 1000 μl) to the dispensing probe channel, move to the reagent carrier containing C solution, and aspirate 300 μl.
2. Move to the set sample, discharge the solution, and suck and discharge 5 times in the sample container to dissolve the pellet.
3. A special tip (octadecyl group is chemically modified) is attached to the dispensing probe channel.
4). Move to a reagent carrier containing methanol, aspirate 200 μl and discharge at the waste port.
5). Move to a reagent carrier containing distilled water, aspirate 200 μl and discharge at the waste port.
6). Move to the reagent carrier containing solution C, aspirate 200 μl and discharge at the waste port.
7). Move to the sample rack. The chip is inserted into the sample solution prepared in the above step, and 200 μl of suction and discharge steps are repeated three times.
8). Move to a reagent carrier containing distilled water, aspirate 200 μl of distilled water and discharge at the waste port.
9. Move to a reagent carrier containing methanol, aspirate 200 μl of methanol, move to a new sample solution tube, and repeat aspiration and discharge of the aspirated solution three times.
10. Above 9. Methanol is removed from this solution with a centrifugal evaporator to obtain a sulfated glycolipid fraction.

  For clinical application, more rapid pretreatment is required. By using such a handling robot, a plurality of samples can be simultaneously processed, and further rapid analysis becomes possible.

The present invention--Example analysis process explanatory diagram Invention-Example analysis explanatory diagram Invention-Example Analysis Result Spectrum Invention-Example Analysis Result Spectrum Invention-Example analysis result structure schematic diagram

Claims (8)

  It consists of the process of selectively purifying only the sulfated glycolipid component from a small amount of biological sample, and further the step of lysing the purified sulfated glycolipid component and removing impurities generated by lyso-formation. And a method for analyzing sulfated glycolipid.   2. The method for analyzing sulfated glycolipids according to claim 1, wherein a monolith structure having a three-dimensional network structure through-hole is used in one or both of the selective purification step and the impurity removal step. .   The method for analyzing sulfated glycolipids according to claim 1 or 2, wherein detection is performed by MALDI / TOF / MS in the selective purification step and the detection step after the impurity removal step.   4. The method for analyzing sulfated glycolipids according to claim 3, wherein sulfated glycolipids in trace amounts of living organisms are identified by comparing the analysis results of MALDI, TOF, and MS obtained in each step.   A monolith structure for analysis of sulfated glycolipids, wherein the three-dimensional network structure has a through-hole of 1 μm to 100 μm.   A monolith structure for analysis of sulfated glycolipids, wherein Si is a main component of a skeleton of a monolith structure having through holes having a three-dimensional network structure.   A monolith structure in which a sulfated glycolipid and its constituent lyso-formation component in a trace biological sample can be purified by reverse phase partitioning by chemically bonding an alkyl chain to the monolith structure.   A solid-phase extraction device comprising a monolith structure is detachably installed in the liquid contact part of the suction and discharge mechanism, and the liquid contact part is provided so as to be movable between the carrier of the solution and the reagent. An apparatus for analyzing sulfated glycolipids, wherein adsorption, washing and elution processes for components are made selectable.

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