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Biochemical and enzymatic characterization of blood group ABH and related histo-blood group glycosphingolipids in the epithelial cells of porcine small intestine.

Non-acid glycosphingolipids were isolated from small intestinal epithelial cells of a single blood group A pig. One very predominant blood group compound was obtained chemically pure upon HPLC fractionation. It was characterized by mass spectrometry and 1H NMR spectroscopy to be the type 1 chain blood group A hexaglycosylceramide. Support for the presence of minute amounts of additional A glycolipids was obtained by mass spectrometry and immunostaining of TLC plates with anti-A antibodies specific for A type 2 chain, A type 3 and 4 chain, and the ALe(b) determinant. Among precursor chains, globoside (type 4) and lactotetraosylceramide (type 1) were immunologically identified, whereas no neolactotetraosylceramide (type 2) and gangliotetraosylceramide reactivities were detected. We addressed the question whether the predominant expression of type 1 chain based A glycolipids reflects a restricted glycolipid precursor chain specificity of the alpha 1-2 fucosyl- and/or the alpha 1-3 N-acetylgalactosaminyltransferases, or if the biosynthesis of the precursor chains themselves is regulated. All precursor core saccharides, lacto- (type 1), neolacto-(type 2), and gangliotetraosylceramide as well as globopentaosylceramide (type 4), could serve as acceptors for fucose in vitro when a crude microsomal fraction obtained from mechanically released, porcine intestinal epithelial cells was used as an enzyme source. Under the same conditions an N-acetylgalactosamine residue could be transferred to the blood group H structures based on these core saccharide chains. Lactotriaosylceramide, but not gangliotriaosylceramide, could serve as an acceptor for UDP-galactose. When the product was digested with beta-galactosidase (EC 3.2.1.23) from S.pneumoniae, under conditions where it specifically cleaves Gal beta 1-4 residues, approximately 40% of the radioactivity was cleaved off, indicating that a substantial amount of neolactotetraosylceramide was made in vitro, as opposed to the predominance of lactotetraosylceramide-based structures found in vivo.

ABO Blood-Group System↗

Lex glycosphingolipids-mediated cell aggregation.

Glycoconjugates bearing oligosaccharide Lex, Galbeta1-->4(Fucalpha1-->3)GlcNAcbeta1-->3R, are found on the surface of several cell types. Although recent studies have indicated that Lexon both glycosphingolipids (GSL) and polylactosaminoglycans can mediate under certain experimental conditions Lex-Lexinteractions, cell-cell interactions based exclusively on LexGSLs have not been demonstrated. In this study we show that preincubation of nonaggregating rat basophilic leukemia (RBL) cells with purified LexGSLs resulted in incorporation of the GSLs into plasma membrane, as determined by immunostaining, and formation of aggregates in the presence of Ca2+; no aggregates were formed after preincubation of the cells with globoside or sphingomyelin. Lex-mediated aggregation was inhibited by removal of Ca2+or by addition of lactofucopentaose III but not by lactose or lacto-N-fucopentaose II. In a mixture of Lex-positive and Lex-negative RBL cells most of the aggregates were composed exclusively of Lex-positive cells. The combined data suggest that interactions between LexGSL on opposite cell surfaces are strong enough to allow formation of stable cell-cell contacts.

Animals↗

Anti-alpha-galactosyl antibodies recognizing epitopes terminating with alpha1,4-linked galactose: human natural and mouse monoclonal anti-NOR and anti-P1 antibodies.

The rare NOR erythrocytes, which are agglutinated by most human sera, contain unique glycosphingolipids (globoside elongation products) terminating with the sequence Galalpha1-4GalNAcbeta1-3Gal- recognized by common natural human antibodies. Anti-NOR antibodies were isolated from several human sera by affinity procedures, and their specificity was tested by inhibition of antibody binding to NOR-tri-polyacrylamide (PAA) conjugate (ELISA) by the synthetic oligosaccharides, Galalpha1-4GalNAcbeta1-3Gal (NOR-tri), Galalpha1-4GalNAc (NOR-di), Galalpha1-4Galbeta1-3Galbeta1-4Glc ((Gal)3Glc), and Galalpha1-4Gal (P1-di). Two major types of subspecificity of anti-NOR antibodies were found. Type 1 antibodies were found to react strongly with (Gal)3Glc and NOR-tri and weakly with P1-di and NOR-di, which indicated specificity for the trisaccharide epitope Galalpha1-4Gal/GalNAcbeta1-3Gal. Type 2 antibodies were specific to Galalpha1-4GalNAc, because they were inhibited most strongly by NOR-tri and NOR-di and were not (or very weakly) inhibited by (Gal)3Glc and P1-di. Monoclonal anti-NOR antibodies were obtained by immunizing mice with NOR-tri-human serum albumin (HSA) conjugate and were found to have type 2 specificity. All anti-NOR antibodies reacted specifically with NOR glycolipids on thin-layer plates. The cross-reactivity of type 1 anti-NOR antibodies with Galalpha1-4Gal drew attention to a possible antigenic relationship between NOR and blood group P system glycolipids. The latter glycolipids include Pk (Galalpha1-4Galbeta1-4Glc-Cer) present in all normal erythrocytes and P1 (Galalpha1-4Galbeta1-4GlcNAcbeta1-3Galbeta1-4Glc-Cer) present only in P1 erythrocytes. Sera of some P2 (P1-negative) persons contain natural anti-P1 antibodies. This prompted us to test the specificity of anti-P1 antibodies. Natural human anti-P1 isolated from serum of P2 individual and mouse monoclonal anti-P1 were best inhibited by Galalpha1-4Galbeta1-4GlcNAc (P1-tri) and did not react with NOR-tri and NOR-di. Monoclonal anti-P1 bound to Pk and P1 glycolipids and not to NOR glycolipids. These results indicated an entirely different specificity of anti-NOR and anti-P1 antibodies. Human serum samples differed in the content of anti-alpha-galactosyl antibodies, including both types of anti-NOR. In the sera of some individuals, type 1 or type 2 anti-NOR antibodies dominated, and other samples contained mixtures of both types of anti-NOR. The biological significance of these new abundant anti-alpha-galactosyl antibodies still awaits elucidation.

Animals↗

Sequential shifts in the three major glycosphingolipid series are associated with B cell differentiation.

Cell surface glycolipid expression as well as total glycolipid content of various B cell lines, representative of different B cell stages, and normal B lymphocytes were examined. Glycolipids, made up of a carbohydrate chain attached to a lipid called ceramide, are classified in four main 'series'. These series are defined according to the identity and chemical bonding of the sugars closest to the ceramide moiety. The pre-B cell lines contained lacto-series type II chain-based glycolipids and II3-alpha-N-acetyl-neuraminosyllactosylceramide (GM3) ganglioside. Upon differentiation, the lacto-series synthesis was shut down whereas compounds of the globo-series appeared: resting lymphocytes and lymphoblastoid cell lines (LCL) expressed GM3, globotriaosylceramide (Gb3), and globoside (Gb4). At a later stage of B cell differentiation, biosynthesis of the ganglio-series was extended and myeloma cells expressed II3-alpha-N-acetyl-neuraminosylgangliotriosylceramide (GM2). At the cell surface, in addition to Gb3, that we previously described as specifically expressed on Burkitt's lymphoma cells and on a subset of germinal centre tonsillar B cells, two glycolipids seemed specific of certain B cell lines: Gb4 was strongly positive on six out of eight LCLs and on the low buoyant density fraction of tonsillar B lymphocytes, whereas GM2 ganglioside was only detected on the two myeloma cell lines. These results, demonstrating the stage-dependent expression of certain glycolipids, suggest that these carbohydrate molecules could play functional roles during B cell differentiation.

Antibodies, Monoclonal↗

Purification and characterization of beta-N-acetylhexosaminidase from the ascidian, Halocynthia roretzi.

beta-N-Acetylhexosaminidase [EC 3.2.1.30] was purified 820-fold from the viscera of Halocynthia roretzi by Sephadex G-200 gel filtration and chromatography on columns of DEAE-Sephadex and CM-Sephadex. The final preparation was sufficiently free from alpha-N-acetylglucosaminidase, alpha-N-acetylgalactosaminidase, alpha- and beta-glucosidases, alpha- and beta-galactosidases, alpha- and beta-mannosidases, and alpha-L-fucosidase, and gave one protein band on disc gel electrophoresis. Two different molecular weight forms which depended upon the pH were observed on Sephadex gel filtration. At pH 7.0, a species with a molecular weight of 170,000 was observed, whereas at pH 4.5, an enzyme of 330,000 daltons was seen. The enzyme was active at pH 4.5 but inactive at pH 7.0. The optimum pH and the Km were pH 4.2 and 1.9 mM for p-nitrophenyl beta-N-acetylglucosaminide and pH 4.0 and 0.9 mM for p-nitrophenyl beta-N-acetylgalactosaminide. The terminal beta-N-acetylhexosamine of glycolipids such as globoside I, GM2, and asialo GM2 was cleaved by the ascidian beta-N-acetylhexosaminidase though GM2 was less susceptible to the enzyme.

Chemical Phenomena↗

Transglycosylation and reverse hydrolysis reactions of endoglycoceramidase from the jellyfish, Cyanea nozakii.

Endoglycoceramidase (EGCase: EC 3.2.1.123) is an enzyme capable of cleaving the glycosidic linkage between oligosaccharides and ceramides in various glycosphingolipids. We report here transglycosylation and reverse hydrolysis reactions of EGCase from the jellyfish Cynaea nozakii. Various alkyl-GM1 oligosaccharides (alkyl-II(3)NeuAcGgOse4) were synthesized when GM1 ganglioside was treated with the EGCase in the presence of 1-alkanols. Among various 1-alkanols tested, methanol was found to be the most preferential acceptor, followed by 1-hexanol and 1-pentanol. GM1 was the best donor, followed by GD1b and GT1b, when methanol was used as an acceptor. However, neither globoside nor glucosylceramide was utilized by the enzyme as a donor substrate. The enzyme transferred oligosaccharides from various glycosphingolipids to NBD-ceramide, a fluorescent ceramide, producing NBD-labeled glycosphingolipids. In addition to the transglycosylation reaction, the enzyme catalyzed the reverse hydrolysis reaction; lactose was condensed to ceramide to generate lactosylceramide in the presence of the enzyme. These results indicate that the jellyfish enzyme will facilitate the synthesis of various neoglycoconjugates and glycosphingolipids.

Alcohols↗

Characterization of the interaction of hemolytic lectin CEL-III from the marine invertebrate, Cucumaria echinata, with artificial lipid membranes: involvement of neutral sphingoglycolipids in the pore-forming process.

The hemolytic lectin, CEL-III, is a Ca2+-dependent, galactose/N-acetylgalactosamine-specific lectin purified from the marine invertebrate, Cucumaria echinata (Holothuroidea). After binding to specific carbohydrates on the erythrocyte surface, CEL-III forms ion-permeable pores by oligomerizing in the membrane, which leads to colloid osmotic rupture of the cells. When incubated with liposomes composed of total lipids from the human erythrocyte membrane, CEL-III efficiently induced the leakage of carboxyfluorescein (CF) trapped in the vesicles, suggesting the presence of its receptor in the membrane lipids. The rate of CF-leakage increased with increasing temperature, although the hemolytic activity of CEL-III had been found to be much higher at lower temperatures (around 10 degrees C). Identification of the receptor for CEL-III was performed by examining the ability of individual lipids from human erythrocytes to induce CF-leakage from DOPC-liposomes. As a result, the most effective receptor was found to be lactosyl ceramide (LacCer), while globoside (Gb4Cer) also showed slight induction of CF-leakage. On the other hand, a binding assay involving CEL-III-horseradish peroxidase conjugate indicated that CEL-III exhibits similar affinity for LacCer and Gb4Cer, suggesting that the structure or length of the carbohydrate portion of sphingoglycolipids is also relevant as to their ability to induce CF-leakage in addition to their affinity. Electron micrographs of CEL-III-treated liposomes revealed that CEL-III induced considerable morphological changes in the vesicles, while a clearly distinguishable oligomeric structure of the protein was not observed.

Animals↗

Glycosphingolipid composition of a renal cell line (MDCK) and its ouabain-resistant mutant.

Glycosphingolipids were isolated from a canine kidney cell line (MDCK) and its ouabain-resistant mutant (MDCK-OR) by solvent extraction, mild alkaline methanolysis, a DEAE-Sephadex column, and preparative TLC. The glycolipids were characterized by their mobilities on TLC, an analysis of carbohydrates as trimethylsilyl methyl glycosides and acetates of partially methylated alditols, as well as by treatment with specific glycosidases. In the neutral glycolipid fraction of both cell lines, galactosylceramide (GalCer), glucosylceramide (GlcCer), lactosylceramide (LacCer), digalactosylceramide (Ga2Cer), globotriaosylceramide (Gb3Cer), globoside (Gb4Cer), and the Forssman antigen (IV3GalNAc alpha-Gb4Cer) were identified. The contents of Ga2Cer (4.4 nmol/mg protein), Gb3Cer (0.6), Gb4Cer (2.9), and IV3GalNac alpha-Gb4Cer (19.5) in MDCK-OR were 1.4- to 2.1-fold higher than those in MDCK, while the concentrations of GlcCer (5.3) and LacCer (1.4) in MDCK-OR were about half of those in MDCK. Among acidic glycolipids of MDCK-OR, galactosyl sulfatide (GalCer-I3-sulfate) and lactosyl sulfatide (LacCer-II3-sulfate) were increased to 1.9 (2.7-fold) and 0.2 nmol/mg protein (2.0-fold), respectively, as compared to MDCK. However, N-acetylneuraminosyllactosylceramide (GM3), the predominant ganglioside in both cell lines, was decreased to about one third of the level (1.5 nmol/mg protein) in the parent MDCK (4.7 nmol/mg protein). The fatty acid of the glycolipids in both cell lines consisted mainly of saturated acids of 16, 18, 22, and 24 carbons.

Animals↗

Glycolipids of mouse erythroleukemia cells (Friend cells) and their alteration during differentiation.

Neutral and acidic glycosphingolipids of Friend cells were characterized in 1) undifferentiated Friend cells (745A), 2) differentiated Friend cells induced with dimethyl-sulfoxide, and 3) solid tumors grown in mice after subcutaneous implantation of Friend cells. The structures of the isolated glycosphingolipids were determined by means of compositional analysis, methylation analysis and enzyme treatment. Gangliosides GD1a and N-acetylgalactosaminyl-GD1a, followed by GM1a and GM2, were the main gangliosides in undifferentiated Friend cells. GD1a and N-acetylgalactosaminyl-GD1a accounted for 45 and 25% of the total gangliosides, respectively. On differentiation, ganglioside GM2 decreased significantly, from 10% to a trace amount. In solid tumors, GD1a was the major ganglioside, whereas in contrast to the situation in the cultured cells, N-acetylgalactosaminyl-GD1a was almost completely absent, and ganglioside GM1b, but not GM1a, was detected. In addition, ganglioside GD1 alpha was detected in the solid tumors. Galactosylceramide, glucosylceramide, and lactosylceramide were the main neutral components in both types of cells, while globotetraosylceramide (globoside), IV3-N-acetyl-galactosaminyl globotetraosylceramide (Forssman glycolipid) and gangliotetraosylceramide (GA1) were major in solid tumors grown in vivo.

Animals↗

Immunochemical and histochemical studies on a phosphonoglycosphingolipid, SGL-II, isolated from the sea gastropod Aplysia kurodai.

Antiserum was raised against 3-O-MeGal beta 1----3GalNAc alpha 1----3[6' -O-(2-aminoethylphosphonyl)Gal alpha 1----2 (2-aminoethylphosphonyl----6)Gal beta 1----4Glc beta 1----1Ceramide (SGL-II) isolated from the skin of a mollusc, Aplysia kurodai. This antiserum reacted with SGL-II and other phosphonoglycosphingolipids of Aplysia such as SGL-I', F-21, and some minor glycolipids on TLC plates, but it did not react with ganglioside or globoside. The sugars recognized were 3-O-methylgalactose at the non-reducing end and galactose at the branched chain of the glycolipids. One membrane glycoprotein (Mr 280,000) reacted strongly, and some other proteins reacted weakly with the antiserum. Immunohistochemical examination of the nervous tissues revealed distinct staining in the periganglionic tissue of the ganglia, and the perineural sheath of the proximal portion of the peripheral nerves. The neuropil and satellite cells were also stained. In the skin, subcutaneous connective tissues were moderately stained, and the cytoplasm of small mononuclear cells and foamy cells was also stained. The staining patterns were essentially the same in paraffin and cryostat sections. From the findings with sections pretreated with chloroform-methanol (2 : 1, v/v), it was suggested that the periganglionic and perineural stainings were due to glycoproteins, including an SDS-soluble glycoprotein of Mr 280,000, while those of the other regions were due to SGL-II and glycolipids immunologically related to SGL-II. The stainings in the skin sections were largely due to glycoproteins.

Animals↗

Different distributions of glycosphingolipids in mouse and rabbit skeletal muscle demonstrated by biochemical and immunohistological analyses.

The expression of neutral glycosphingolipids and gangliosides was investigated in mouse and rabbit skeletal muscle by means of biochemical and immunochemical techniques. Neutral glycosphingolipids from muscle of the inbred rabbit strain used in this study showed a simple TLC pattern, comprising mainly monohexosylceramide. In addition to this compound, lactosylceramide, lacto-N-neotetraosylceramide, globoside and Forssman GSL were detected in mouse muscle. The major ganglioside in both species was GM3; GM3 (Neu5Ac) and GM3(Neu5Gc) were found in a 3:1 ratio in mouse muscle, whereas the absence of GM3(Neu5Gc) is characteristic of rabbit muscle. As a general structural feature of all muscle GM3 gangliosides investigated, a C18 fatty acid and C18 sphingosine were the major components besides minor C22 and C24:1 fatty acids of the respective ceramide portions, as revealed by positive and negative ion FAB-MS. alpha 2-3 sialylated lacto-N-neotetraosyl-ceramide (sialylparagloboside) was expressed in both species, whereas the alpha 2-6 sialylated isomeric compound was found only in mouse muscle. Minute quantities of ganglio-series GM1, GD1a, GD1b, and GT1b were detected in muscles from both species. Glycosphingolipid expression could be confirmed immunohistochemically by examining transverse and longitudinal cryosections of skeletal muscle samples. The results provide the basis for the investigation of muscle specific glycosphingolipids that might modulate membrane protein functions in muscle.

Animals↗

Purification and characterization of beta-N-acetylhexosaminidases and beta-galactosidase from Streptococcus 6646 K.

Three beta-N-acetylhexosaminidases [EC 3.2.1.52] and one beta-galactosidase [EC 3.2.1.23] were purified from the culture filtrate of streptococcus 6646 group K by a combination of column chromatographies on p-aminophenyl beta-D-thiogalactopyranoside-substituted Sepharose and N-(paminophenyl)oxamic acid-substituted Sepharose. These beta-N-acetylhexosaminidases showed optimal activities between pH 5.0 and 5.5 and could hydrolyze synthetic and glycopeptidic substrates. Glycolipids such as GM2, asialo-GM2, and globoside I were no susceptible to these beta-hexosaminidases. beta-Galactosidase, which was purified more than 11,000-fold, had a substrate specificity rather similar to that of beta-galactosidase from E. coli. This enzyme was inhibited by EDTA and activated by Mn2+, Ca2+, and Mg2+. Problems pertinent to the application of affinity chromatography to the purification of glycosidases are also discussed.

Cations, Divalent↗

Comparative study of glycolipid compositions of plasma membranes among two types of rat ascites hepatoma and normal rat liver.

Glycolipid composition of purified plasma membranes from rat ascites hepatomas, two island-forming cell-lines and two cell-lines of the free-type, and normal rat liver were compared. Ceramide monohexoside (CMH), ceramide dihexoside (CDH), and hematoside (GM3) were found in normal rat liver cell membranes. The island-type hepatomas contained ceramide trihexoside (CTh) and globoside besides CMH, CDH, and GM3. The free-type of hepatomas were characterized by the presence of asialo-type gangliosides but not GM3. The free-type of hepatomas were characterized by the presence of asialo-type gangliosides but not GM3. Blood group H active fucolipid was a major glycolipid in the free-type of ascites hepatoma cell (AH 7974 F). The increase of glycolipid content in cell membranes seemed to be accompanied with a decrease of cell adhesiveness.

ABO Blood-Group System↗

Blood group type glycosphingolipids from the small intestine of different animals analysed by mass spectrometry and thin-layer chromatography. A note on species diversity.

The total non-acid glycosphingolipids were isolated from the small intestine of cat, cod-fish, guinea-pig, hen, mouse, rabbit, and two strains of rat. The samples were analyzed by thin-layer chromatography and mass spectrometry and for immunological activity. Mass spectrometry of permethylated and LiAlH4-reduced permethylated derivatives allowed the interpretation of the structures (carbohydrate sequence and ceramide composition) of up to 9 glycolipid species in one mixture. The interpretation was facilitated by a temperature programming of the direct inlet probe, leading to a successive evaporation of glycolipid species mainly according to the number of sugars. The structures concluded could in most cases be assigned to the separate bands revealed by thin-layer chromatography. Antigenic determinants proposed by the spectra were settled by immunological analysis. Thus, Forssman glycolipid was identified in cat, guinea-pig, hen and mouse, blood group A glycolipids in cat, rabbit, and rat and blood group B glycolipids in rabbit and rat. No Lewis activity was found. Certain ceramide types were demonstrated to exist preferentially in some glycolipids. Globoside and Forssman glycolipids (globo series) had a less hydroxylated ceramide (one free hydroxyl) compared to most fucolipids and other glycolipids (two or three hydroxyls). In conclusion, glycolipid patterns of intestine vary between species, and individuals of the same species.

ABO Blood-Group System↗

Intermolecular interaction between glycolipids and glycophorin on liposomal membranes.

The haptenic activity of Forssman glycolipid was affected by glycophorin, and the interaction of glycophorin with lectins was also affected by the glycolipids, when both glycophorin and Forssman glycolipid or globoside were incorporated into the same phosphatidylcholine liposomes. Glycophorin incorporated into phospholipid membranes could interact with lectins, whereas that in glyceroglycolipid membranes could not. These findings suggest that glycophorin and glycolipids may interact, affecting the conformation of their sugar residues, probably through a carbohydrate-carbohydrate interaction. Such an interaction may cause suppression or stimulation of the reactivity of glycoconjugates with lectins or antibodies. Lactosylceramide showed only a slight effect on the interaction between glycophorin and lectins. We suggest that the structure of the sugar residues as well as the lateral distribution of molecules was important for the intermolecular interaction.

Animals↗

Differential reactivities of fucosyl GM1 and GM1 gangliosides on rat erythrocyte membrane revealed by analysis with anti-fucosyl GM1 and GM1 antisera.

Rat erythrocytes contained ganglio-series gangliosides, GM1, fucosyl GM1, and GD1a, in a high concentration. The concentrations of GM1, fucosyl GM1, and GD1a in rat erythrocyte ghosts were 889.0 nmol, 470.6 nmol, and 462.0 nmol per g dry weight, respectively, and the molar ratio of lipid-bound sialic acid, cholesterol and lipid-bound phosphorus was 3.1:73.9:100.0. The reactions of fucosyl GM1 and GM1 on rat erythrocytes with rabbit anti-fucosyl GM1 and anti-GM1 antisera were measured by means of haemolysis in the presence of complement and a binding assay of antibodies with a FACS after staining erythrocytes by the indirect membrane immunofluorescence technique. When measured by ELISA, anti-fucosyl GM1 antiserum was found to react almost exclusively with fucosyl GM1 with a slight cross-reaction with GM1, but anti-GM1 antiserum cross-reacted to a significant extent with asialo GM1. Rat erythrocytes were haemolyzed specifically with anti-fucosyl GM1 antiserum, but not with antisera to GM1, asialo GM1, asialo GM2, Forssman and globoside, and the haemolysis was proved to be definitely caused by the specific recognition of fucosyl GM1 on rat erythrocytes by anti-fucosyl GM1 antibody according to the haemolysis inhibition reaction using various glycosphingolipid-containing liposomes as inhibitors. In addition, although the binding of anti-fucosyl GM1 antibody on rat erythrocytes was clearly demonstrated with a FACS, anti-GM1 antibody did not bind. The observations that the haemolysis of rat erythrocytes and the binding of antibody to rat erythrocytes were found only with anti-fucosyl GM1 antiserum, and not with anti-GM1 antiserum, but that nevertheless the titer of anti-GM1 antiserum was higher than that of anti-fucosyl GM1 antiserum and GM1 on rat erythrocytes was more abundant in concentration than fucosyl GM1, seem to be a matter of great importance in assessing the specificity of anti-ganglioside antibody and the surface distribution of gangliosides on the cell.

Animals↗

The separation of neutral glycosphingolipids from mammalian erythrocytes by droplet counter-current chromatography (DCC).

In a previous paper (Otsuka, H. & Yamakawa, T. (1981) J. Biochem. 90, 247-254), we reported the separation of acidic glycolipids by droplet counter-current chromatography using 500 columns with a commercially available DCC apparatus and described the precise conditions of the separation. In this paper, separation of neutral glycolipids from rabbit and human erythrocytes by DCC is described. For efficient separation of neutral glycolipids, addition of a definite amount of benzene was required. The solvent system of chloroform: benzene: methanol: water = 50: 50: 70: 20 gave clear separation of these glycolipids and further modification of this solvent system to chloroform: benzene: methanol: water = 50: 25: 65: 30 gave satisfactory results for the separation of Globoside I from human erythrocytes due to the difference between the amide linked fatty acids. Also under the same conditions, the clear separation of two peaks with blood group A activity was demonstrated by a hemagglutination inhibition test.

ABO Blood-Group System↗

Positive and negative ion fast atom bombardment mass spectrometry of glycosphingolipids. Discrimination of the positional isomers of gangliosides with sialic acids.

High molecular weight gangliosides (GD1a, GD1b, GT1a, and GT1b) and neutral glycosphingolipids (Forssman antigen, globoside, and CTH) containing various fatty acids were analyzed by positive and negative ion fast atom bombardment mass spectrometry (POS-FAB-MS and NEG-FAB-MS) without any derivatization. NEG-FAB-MS of the molecules gave intense peaks of the molecular ion species, (M-H)-, and many fragment ions useful for the elucidation of carbohydrate structure were also detected with significant intensity. The fragment ions were assessed to be cleaved at the glycosidic linkages sequentially from the non-reducing end with or without the ceramide portion and it was possible to distinguish structural isomers having different binding positions of sialic acid. All molecular ion species of neutral glycosphingolipids with various fatty acids were detected at intensities that were in accordance with the relative abundance of the fatty acids.

Animals↗