Main structures of the Forssman glycolipid hapten and a Leb-like glycolipid of dog small intestine, as revealed by mass spectrometry. Difference in ceramide structure related to tissue localization

Urinary globotriaosylsphingosine-related biomarkers for Fabry disease targeted by metabolomics

Fabry disease is a lysosomal storage disorder caused by deficiency of α-galactosidase A, resulting in glycosphingolipid accumulation in organs and tissues, including plasma and urine. Two disease-specific Fabry biomarkers have been identified and quantified in plasma and urine: globotriaosylceramide (Gb(3)) and globotriaosylsphingosine (lyso-Gb(3)). The search continues for biomarkers that might be reliable indicators of disease severity and response to treatment. The main objective of this study was to target other urinary biomarkers using a time-of-flight mass spectrometry metabolomic approach. Urinary metabolites of 63 untreated Fabry patients and 59 controls were analyzed. A multivariate statistical analysis performed on a subset of male samples revealed seven novel Fabry biomarkers in urine, all lyso-Gb(3) analogues having modified sphingosine moieties. The empirical formulas of the sphingosine modifications were determined by exact mass measurements (- C(2)H(4), - C(2)H(4) + O, - H(2), - H(2) + O, + O, + H(2)O(2), + H(2)O(3)). We evaluated the relative concentration of lyso-Gb(3) and its seven analogues by measuring area counts for each analogue in all Fabry patients. All samples were normalized to creatinine. We found higher concentrations for males with Fabry disease compared to females. None of these biomarkers were detected in controls. To our knowledge, this is the first time that lyso-Gb(3)-related Fabry disease biomarkers are detected in urine.

Structure and antigenicity of the major glycolipid from Taenia solium cysticerci

Lipids were extracted from cysticerci of the human tapeworm Taenia solium isolated from various infected pigs and analysed by two-dimensional thin-layer chromatography. These consisted of both alkali-labile and alkali-stable glycolipids, and phosphorylated non-glycosylated lipids. Because abundant and immunogenic glycolipids of parasites have been implicated in host-parasite interactions, the major lipid, an alkali-stable glycolipid, was purified by chromatography and its structure and antigenicity were determined. The structure of the major glycolipid of T. solium, GSL-I, was elucidated through a combination of chemical degradative methods, gas chromatography/mass spectrometry analyses of the degradative products, matrix-assisted-laser desorption/ionisation time of flight mass spectrometry and nuclear magnetic resonance spectroscopy. This analytical strategy led to the identification of a family of beta-galactosylceramides composed mainly of phytosphinganine (2-hydroxylated sphinganine) N-acylated by C16-C24 fatty acids, with the predominance of 2-hydroxylated homologues. Enzyme-linked immunosorbent assay showed no correlation between the antibody titres directed against GSL-I in the human sera and the infective status; in contrast, a very high specific immunoreactivity and a sensitivity above 50% were observed when GSL-I was tested with cerebrospinal fluids from well characterised infected humans. Thus, although these results do not support the use of GSL-I alone as an antigen for the detection of neurocysticercosis, its use as part of an antigen cocktail for the diagnosis of the disease in cerebrospinal fluids merits further investigations.

Different O-glycosylation of respiratory mucin glycopeptides from a patient with cystic fibrosis

The O-linked oligosaccharides from three fractions of highly glycosylated mucin glycopeptides obtained from sputum of a patient with cystic fibrosis were characterized and compared regarding size, composition, sequence and when possible linkage positions. Neutral and sialic acid-containing glycans were permethylated and analyzed by high-temperature GC-MS and MALDI-MS, showing more than 60 different oligosaccharides with a size of up to 15 monosaccharide units. Some of the observed oligosaccharides are novel for respiratory secretions, one being a trifucosylated heptasaccharide with the proposed structure: Fuc-Gal-4(Fuc-3)GlcNAc-(Fuc-)Gal-3GalNAcol. The glycosylation of two of the glycopeptide fractions was similar with regard to the neutral and sialylated oligosaccharides despite their different origins from the sol or gel phase. Analysis of the sulfated oligosaccharides by FAB-MS/MS indicated that the gel fraction contained C-6 linked sulfate groups while the two sol fractions also contained C-3 linked sulfate. The results suggest the presence of different glycosylated mucin domains, probably originating from different mucin glycoforms and/or apoproteins in the airway of cystic fibrosis patients.

The glycosylation of rat intestinal Muc2 mucin varies between rat strains and the small and large intestine. A study of O-linked oligosaccharides by a mass spectrometric approach

The large glycosylated domains obtained from the rat intestinal mucin Muc2 were isolated from the large and small intestine of the inbred rat strains GOT-W and GOT-BW. The expression of the rat Muc2 in the large intestine was confirmed immunochemically and by Northern blotting. Released oligosaccharides were structurally characterized by gas chromatography-mass spectrometry (neutral and sialylated species) or by tandem mass spectrometry (sulfated species), and a total of 63 structures was assigned. The large intestinal oligosaccharides were found to be identical between the strains, while the small intestinal glycosylation differed. Until now, detailed structural analysis of oligosaccharides isolated from a single mucin core or mucin domain with different origin have not been performed, and the information of different mucin glycoforms has been limited to immunochemistry. Blood group A-determinants (GalNAcalpha1-3(Fucalpha1-2)Galbeta1-, and structures related to the blood group Sda/Cad-related epitope NeuAc/NeuGcalpha1-3(GalNAcbeta1-4)Galbeta1-, were found in GOT-BW small intestine, and also in both large intestines. Blood group H-determinants and NeuAc/NeuGcalpha1-3Galbeta1- were found in all samples. Core 1 (Galbeta1-3GalNAcalpha1-), core 2 (Galbeta1-3(GlcNAcbeta1-6)GalNAcalpha1-), core 3 (GlcNAcbeta1-3GalNAcalpha1-), and core 4 (GlcNAcbeta1-3(GlcNAcbeta1-6)GalNAcalpha1- were also found in all the samples. The large intestine were enriched in sulfated oligosaccharides and the small intestine contained higher amounts of sialylated species. Sulfation were found exclusively on C-6 of GlcNAc.

An antigen present in rat adenocarcinoma and normal colon non-epithelial stroma is a novel Forssman-like glycolipid based on isoglobotetraosylceramide

A glycolipid with blood group A activity detected in the non-epithelial stroma of normal rat colon but not in epithelial cells (Hansson, G.C., Karlsson, K.-A., and Thurin, J. (1984) Biochim. Biophys. Acta 792, 281-292), was purified to homogeneity from normal rat colon and rat colon adenocarcinoma. Mass spectrometry and 1H-NMR spectroscopy of the intact permethylated derivative and gas chromatography after degradation revealed the structure GalNAc alpha 1----3GAINAc beta 1----3Gal alpha 1----3Gal beta 1----4Glc beta 1----1Cer, with the predominant ceramide containing sphingosine and non-hydroxylated 24:0 fatty acid. This identifies this glycolipid as a novel Forssman-like glycolipid, which is a tumor-associated antigen by definition, since it is not present in the normal rat large intestinal epithelium cells but in rat adenocarcinoma derived from these cells.

A monoclonal antibody against human colonic adenoma recognizes difucosylated Type-2-blood-group chains

A monoclonal antibody C14/1/46/10 showing preferential binding to membranes of human colorectal carcinomas over normal colon mucosae was obtained by immunization of mice with extra-nuclear membranes of a human colonic adenoma. Binding and inhibition of binding assays using blood cells or glycoproteins with known blood-group activities indicated that the antibody recognizes a carbohydrate antigen co-existing with the blood-group-H determinant: Fuc alpha 1 leads to 2 Gal. Inhibition assays with structurally defined oligosaccharides showed that the antigenic determinant involves difucosylated Type-2-blood-group chains with the structure: (formula; see text)

Carbon-13 nuclear-magnetic-resonance spectroscopy of Forssman hapten

The 13C n.m.r. spectrum of Forssman hapten was obtained at 25.16 MHz in [3H] chloroform/[2H] methanol (1:1, v/v), using purified glycosphinogolipid from canine intestinal mucosa (glycolipid I). All amide, olefin, anomeric, intersaccharide glycosidic ether, amide linkage, methyl and many methylene resonances were resolved and assigned. Analysis of the anomeric region reveals the following pentaglycosylceramide structure as originally proposed [Siddiqui & Hakomori (1971) J. Biol. Chem. 246, 5766-5769]: GalNAc (alpha 1 leads to 3) GalNAc (beta 1 leads to 3) Gal (alpha 1 leads to 4) Gal (beta 1 leads to 1) ceramide. Analysis of the amide, olefin and methylene regions reveals no alpha-hydroxy fatty acyl group and less than or equal to 6 mol% unsaturated fatty acyl groups are present. Chemical-shift assignments are reported for the anomeric and glycosidic ether carbon atoms of intersaccharide-linked alpha-galactose and N-acetyl-alpha-galactosamine residues. Two rules are proposed for the assignment of the anomeric form of 1 leads to 3 and 1 leads to 4 linkages of galactose and N-acetylgalactosamine residues present in the glycone of glyco-conjugates. The present study emphasizes the importance of the anomeric "window" (80-120 p.p.m.) in studies of glycone structure.

Synthesis of glycolipids

The chemical syntheses of naturally occurring glycolipids derived from sphingosine bases and glycerol derivatives, and the syntheses of polyisoprenoid lipid intermediates and other miscellaneous glycolipids recorded up to the end of 1977 are reviewed.

Selected ion monitoring of glycospingolipid mixtures. Identification of several blood group type glycolipids in the small intestine of an individual rabbit

A novel application of selected ion monitoring was used for a mixture of non-acid glycosphingolipids of one rabbit small intestine. Earlier studies of permethylated and permethylated-reduced (LiAIH4) derivatives of model compounds have revealed a specificity and abundance of saccharide ions (terminal monosaccharide(s), disaccharide, trisaccharide, etc., and all sugars plus fatty acid) and of ceramide fragments that permit a conclusive detection of separate glycolipid species in a mixture. The sample (50-200 micrograms) was evaporated slowly (1-5 degrees C min-1 from 150-350 degrees C) from the direct inlet probe of an MS 902 mass spectrometer (electron ionization). Mass spectra with fragments up to about m/z 200 were collected on-line by a computer system. A successive partial separation was obtained for glycolipids with from one up to seven sugars. The structures of eight different compounds were identified. They all had 16:0, 22:0 and 24:0 2-hydroxy fatty acids and 18:0 trihydroxy base (phytosphingosine) as major ceramide components. The dominating complex glycolipid was a hexaglycosylceramide with a blood group B type of sequence. A blood group A type sequence was found in a second hexaglycosylceramide. In support of this, the native mixture showed blood group A and B activity. An intense peak, m/z 182, collected from methylated derivatives were evidence for a dominating type 2 carbohydrate chain of the core tetrasaccharide.

Forssman glycolipid variants of dog gastric mucosa. Structure of a branched ceramide octasaccharide

A fucose-containing ceramide octasaccharide exhibiting Forssman antigenic activity, and reacting in human H anti-H and anti-A systems, was isolated from water-soluble glycolipids of dog gastric mucosa. Defucosylation of the glycolipid resulted in the loss of H-activity, but had no effect on its Forssman nor blood-group A antigenic activity. The branched structure of glycolipid was identified by partial acid hydrolysis, sequential degradation with specific glycosidases and comparison of the permethylation products of the native and enzyme-degraded compound. The structure of this glycolipid is proposed to be: formula.

Structural studies on branched fucosphingolipids of hog gastric mucosa

A structural studies have been performed on new complex glycolipids extracted from hog gastric mucosa by 0.4 M sodium acetate in methanol-chloroform-water, and which were purified to homogeneity by DEAE-Sephadex and Florisil column chromatography and by preparative thin-layer chromatography in three solvent systems. Five branched fucolipids have been purified from this extract, three of which have been characterized previously [1] and remaining two were subject of this investigations. Based on the results of partial acid hydrolyses, oxidation with periodate and chromium trioxide, permethylation and serological activities following structures were proposed.

Water-soluble glycosphingolipids of dog gastric mucosa. Characterization of a branched ceramide heptasaccharide

Two glycosphingolipids, the carbohydrate portion of which consisted of galactose, glucose and N-acetylgalactosamine, have been isolated from the aqueous phase of buffered tetrahydrofuran extract of dog gastric mucosa. The structures of these glycolipids were identified by partial acid hydrolysis, sequential degradation with specific glycosidases and methylation analysis. The structure of glycolipid I (GalNAcalpha1 leads to 3GalNAcbeta1 leads to 3Galalpha1 leads to 4Galbeta1 leads to 4Glc leads to ceramide) was found to be identical to that of Forssman hapten. The branched structure of glycolipid II, as determined by the combination of enzymatic degradation and comparison of the permethylation products of the enzyme-degraded compounds, is proposed to be: See Source.

Structural analysis by mass spectrometry of the major mammalian retinal ganglioside, a sialyl-sialyl-dihexosyl-ceramide

The major mammalian retinal ganglioside was analysed by mass spectrometry. Three types of derivatives were used, the fully methylated, the methylated and reduced and the methylated, reduced and trimethylsilylated compound. The mass spectra unambiguously showed the ganglioside to be a sialyl-sialyl-dihexosyl-ceramide. This is the first conclusive proof that the two N-acetylneuraminic acids are bound to each other constituting the terminal disaccharide. The major species contained sphingosine and stearic acid.

Branched blood group A-active fucolipids of hog gastric mucosa

New complex glycolipids have been extracted from hog gastric mucosa with the mixture of 0.4 M sodium acetate in methanol/chloroform/water. Three A-active fucolipids having branched carbohydrate chains have been purified from this extract. The postulated structures of these glycolipids are based on the results of partial acid hydrolysis, oxidation with periodate and chromium trioxide, and permethylation studies.

Molecular arrangements in sphingolipids. Conformation and hydrogen bonding of ceramide and their implication on membrane stability and permeability

The preferred conformation of the ceramide part of sphingolipids has been deduced from single crystal structures of a series of sphingolipid constituents: N-tetracosanoylphytosphingosine, glycosylphytosphingosine hydrochloride, sphingosine hydrochloride, triacetylsphingosine, DL-2-hydroxytetradecanoic acid and N-stearoylethanolamine. The amide group of the ceramide, which serves as a link between the hydrocarbon chains, has a basic significance for the contormation of the entire molecule. This rigid group, which comprises six atoms in a planar conformation, adopts a perpendicular orientation towards the axes of the two hydrocarbon chains. The carbonyl oxygen thereby turns into an eclipsed position with the hydrogen atoma at carbon atom 2 of the sphingosine. A parallel chain stacking is achieved by a sharp perpendicular bend of the fatty acid. This bend is produced by a sequence of two --60 degrees rotations about the C-C bonds at both sides of the alpha-carbon atom. The orientation of the hydrogen bond donors and acceptors of the amide group and the hydroxyl groups allow lateral interaction with other lipid molecules. The proposed models are supported by infrared spectra, thin-layer chromatographic behaviour and monolayer studies of synthetic model ceramides. The functional role of the hydrogen bonding groups in the ceramide part of sphingolipids is emphasized and their significance for the formation of lateral hydrogen bonds within the membrane layer and thereof arising effects on membrane stability and permeability are discussed.

The glycosphingolipids of rat sublingual and submaxillary glands

1. Glycosphingolipids have been isolated from rat sublingual and submaxillary glands by the procedure involving lipid extraction, column fractionation and thin-layer chromatography. 2. The major neutral glycosphingolipids in rat sublingual and submaxillary glands were monohexosylceramide, dihexosylceramide, tetrahexosylceramide and pentahexosylceramide. Both types of glands exhibited a low content of trihexosylceramide. The fucose-containing glycosphingolipids were not found. 3. The acidic glycosphingolipids in rat sublingual and submaxillary glands were composed of monohexose sulfatide, dihexose sulfatide and monosialo-and disialogangliosides of hematoside series. In addition, small quantities of gangliosides containing hexosamines were also present. 4. The distribution of acidic and neutral glycosphingolipids was similar in the sublingual and submaxillary glands, except for the tetrahexosylceramide and sultatides. Sublingual glands contained 1.5 and 3.0 times as much tetrahexosylceramide and sulfatides, respectively, as did submaxillary glands. 5. The glycosphingolipids of submaxillary and sublingual glands showed large similarity in fatty acid composition. The fatty acid composition of gangliosides resembled each other, but differed remarkably from those of sulfatides and neutral glycosphingolipids in the docosanoate content.

Enzymatic synthesis of two fucose-containing glycolipids with fucosyltransferases of human serum

Lacto-N-neotetraosylceramide incubated with human serum fucosyltransferase preparations gave rise to two fucoglycolipids. The faster migrating fucoglycolipid I on the basis of its thin-layer chromatographic mobility, susceptibility to alpha(1 leads to 2) fucosidase from Trichomonas foetus, radio-immunoprecipitation with Ulex europeus lectin and studies with Oh (Bombay) sera was identified as H-active glycolipid (H-I). The most probable structure of fucoglycolipid II should be that with fucose linked alpha(1 leads to 3) to N-acetylglucosamine. Lactosylceramide, ceramide trihexoside and globoside were not substrates for human serum fucosyltransferases. Lacto-N-neotetraosyl ceramide served as a fucose acceptor for all serum preparations tested while asialoganglioside was a substrate only when serum preparations containing H-gene dependent alpha-2-L-fucosyltransferase were used. With asialoganglioside only one radioactive reaction product was formed.

On a molecular, microscale fingerprinting of gangliosides

Mass spectrometry of intact ganglioside derivatives has been shown to afford a specific information on type, number and sequence of sugars, as well as ceramide structure. This is illustrated here for a hematoside with N-glycolylneuraminic acid and a disialyldihexosylceramide. As shown elsewhere, this novel technique, needing only 10 micrograms for a spectrum, is generally applicable to all types of glycolipids, including complex blood group fucolipids.