Structures of gangliosides from bovine adrenal medulla

The Structural Diversity of Natural Glycosphingolipids (GSLs)

Glycosphingolipids (GSLs) are a subclass of glycolipids made of a glycan and a ceramide that, in turn, is composed of a sphingoid base moiety and a fatty acyl group. GSLs represent the vast majority of glycolipids in eukaryotes, and as an essential component of the cell membrane, they play an important role in many biological and pathological processes. Therefore, they are useful targets for the development of novel diagnostic and therapeutic methods for human diseases. Since sphingosine was first described by J. L. Thudichum in 1884, several hundred GSL species, not including their diverse lipid forms that can further amplify the number of individual GSLs by many folds, have been isolated from natural sources and structurally characterized. This review tries to provide a comprehensive survey of the major GSL species, especially those with distinct glycan structures and modification patterns, and the ceramides with unique modifications of the lipid chains, that have been discovered to date. In particular, this review is focused on GSLs from eukaryotic species. This review has listed 251 GSL glycans with different linkages, 127 glycans with unique modifications, 46 sphingoids, and 43 fatty acyl groups. It should be helpful for scientists who are interested in GSLs, from isolation and structural analyses to chemical and enzymatic syntheses, as well as their biological studies and applications.

Liver gangliosides of various animals ranging from fish to mammalian species

Liver gangliosides of different animal species were analyzed. Bony fish liver contained a major ganglioside that migrated faster than GM3 on thin-layer chromatography (TLC). This ganglioside was identified to be GM4 (NeuAc) by methods including product analysis after sialidase treatment and negative-ion electrospray ionization (ESI)-mass spectrometry (MS). The presence of GM4 (NeuGc) in fish liver was also demonstrated. The main ganglioside band of bovine liver consisted of two different molecular species, i.e. GD1a (NeuAc/NeuAc) and GD1a (NeuAc/NeuGc). Major gangliosides of liver tissue exhibited a distinct phylogenetic profile; GM4 was expressed mainly in lower animals such as bony fish and frog liver, whereas mammalian liver showed ganglioside patterns with smaller proportions of monosialo ganglioside species. While c-series gangliosides were consistently expressed in lower animals, they were found only in mammalian liver of particular species. No apparent trend was observed between the concentration of liver gangliosides and the phylogenetic stage of animals. The present study demonstrates the species-specific expression of liver gangliosides.

Plasma membrane lipids of bovine adrenal chromaffin cells

The lipid composition of plasma membranes isolated from bovine adrenal chromaffin cells has been determined. Choline and ethanolamine phosphatides were predominant; the level of lyso compounds was very low. The amount of cholesterol and the cholesterol/phospholipid molar ratio was low compared to those of the other subcellular fractions of chromaffin cells. A complex pattern of neutral glycolipids was observed in contrast to that of gangliosides.

Glycosphingolipids of human plasma

A number of glycosphingolipids, including 10 gangliosides, not previously identified in human plasma have been characterized. The plasma contains 2 micrograms of lipid-bound sialic acid/ml plasma and 54% of the gangliosides are monosialo, 30% disialo, 10% trisialo, and 6% tetrasialo. Individual glycosphingolipids were purified by high-performance liquid chromatography and thin-layer chromatography, and were characterized on the basis of their chromatographic mobility, carbohydrate composition, hydrolysis by glycosidases, methylation analysis, and immunostaining with anti-glycosphingolipid antibodies. The monosialogangliosides were identified as GM3, GM2, sialosyl(2-3)- and sialosyl(2-6)lactoneotetraosylceramides, sialosyllacto-N-nor-hexaosylceramide, and sialosyllacto-N-isooctaosylceramide. The major gangliosides in the polysialo fractions contained a ganglio-N-tetraose backbone and were identified as GD3, GD1a, GD1b, and GQ1b. The most abundant neutral glycosphingolipids were glucosyl, lactosyl, globotriaosyl, globotetraosyl and lactoneotetraosylceramides. The other neutral glycosphingolipids, tentatively identified by immunostaining with monoclonal antibodies, contained H1, Lea, Leb, and lacto-N-fucopentose III (X hapten) structures.

Lipids of nervous tissue: composition and metabolism

As indicated in the Introduction, the many significant developments in the recent past in our knowledge of the lipids of the nervous system have been collated in this article. That there is a sustained interest in this field is evident from the rather long bibliography which is itself selective. Obviously, it is not possible to summarize a review in which the chemistry, distribution and metabolism of a great variety of lipids have been discussed. However, from the progress of research, some general conclusions may be drawn. The period of discovery of new lipids in the nervous system appears to be over. All the major lipid components have been discovered and a great deal is now known about their structure and metabolism. Analytical data on the lipid composition of the CNS are available for a number of species and such data on the major areas of the brain are also at hand but information on the various subregions is meagre. Such investigations may yet provide clues to the role of lipids in brain function. Compared to CNS, information on PNS is less adequate. Further research on PNS would be worthwhile as it is amenable for experimental manipulation and complex mechanisms such as myelination can be investigated in this tissue. There are reports correlating lipid constituents with the increased complexity in the organization of the nervous system during evolution. This line of investigation may prove useful. The basic aim of research on the lipids of the nervous tissue is to unravel their functional significance. Most of the hydrophobic moieties of the nervous tissue lipids are comprised of very long chain, highly unsaturated and in some cases hydroxylated residues, and recent studies have shown that each lipid class contains characteristic molecular species. Their contribution to the properties of neural membranes such as excitability remains to be elucidated. Similarly, a large proportion of the phospholipid molecules in the myelin membrane are ethanolamine plasmalogens and their importance in this membrane is not known. It is firmly established that phosphatidylinositol and possibly polyphosphoinositides are involved with events at the synapse during impulse propagation, but their precise role in molecular terms is not clear. Gangliosides, with their structural complexity and amphipathic nature, have been implicated in a number of biological events which include cellular recognition and acting as adjuncts at receptor sites. More recently, growth promoting and neuritogenic functions have been ascribed to gangliosides. These interesting properties of gangliosides wIll undoubtedly attract greater attention in the future.(ABSTRACT TRUNCATED AT 400 WORDS)

Fucosyl gangliosides of PC12 pheochromocytoma cells

Three monosialogangliosides are highly labeled when PC12 pheochromocytoma cells are cultured in the presence of L-[3H]fucose, and two additional monosialogangliosides are labeled to a lesser extent. In contrast, neither of the two disialogangliosides of PC12 cells contains fucose residues. Removal of sialic acid and fucose by formic acid hydrolysis demonstrated the presence of 3 major 'core' structures in the monosialogangliosides, and a single asialo derivative of the disialogangliosides which has the same chromatographic mobility as one of the monosialoganglioside hydrolysis products. None of the major formic acid hydrolysis products of the PC12 cell gangliosides corresponds to asialo-GM1, supporting our previous conclusion that PC12 cells do not contain significant amounts of brain-type gangliosides.

Isolation and characterization of a novel disialoganglioside from bovine adrenal medulla

A novel GDlb ganglioside which contains only N-glycolylneuraminic acid was isolated from bovine adrenal medulla by DEAE-Sephadex A-25 and Iatrobeads column chromatography. The concentration of this ganglioside was 0.9 nmol lipid-bound sialic acid per gram fresh tissue, which accounted for 2.7% of the disialoganglioside fraction. The structure was elucidated by sugar analysis, neuraminidase digestion, and permethylation studies. The complete structure of this ganglioside was identified as GDlb (NeuGc)2 or II3 (NeuGc)2-GgOse4Cer.

Adrenal medulla gangliosides

The gangliosides were examined in adrenal glands of mouse, rat, guinea pig, rabbit, monkey, pig, ox and chicken. GM3 ganglioside was predominant in all examined animals except pig. In pig GD3 ganglioside was the major one. GM4 ganglioside was found in guinea pig and chicken. The distribution of sialic acid varied in each species. NeuNGly containing gangliosides were not detected in rat, guinea pig, rabbit and chicken. The other animals have both NeuNAc and NeuNGly containing gangliosides. Chromaffin granules from bovine adrenal medulla contain gangliosides at concentrations 3 and 7 times as great as microsomal and mitochondrial fractions, respectively. These gangliosides were NeuNAc-containing GM3 and NeuNGly containing GM3 in the same amount.

The topography of gangliosides in the membrane of the chromaffin granule of bovine adrenal medulla

We have studied the topography of the gangliosides of the adrenal chromaffin granules by using neuraminidase to remove sialic acid from membrane gangliosides of intact and ruptured chromaffin granules. Residual sialic acid was then measured to compare the availability of gangliosides on the outer and inner surfaces of the membrane. Measurement of protein sialic acid served as a control since these residues are known to be on the inner surface of the membrane. Prolonged digestion of broken membranes showed that maximally 75% of both lipid and protein-bound sialic acid residues are available to neuraminidase. Prolonged digestion of intact granules produced no measureable loss of sialic acid from either protein or lipid fractions. Comparison of the thin-layer chromatograms of gangliosides extracted from digested and undigested membranes showed no preferential digestion of any component. We conclude that at least 75% of the gangliosides are on the inner leaflet of the membrane and suggest that all of the gangliosides are so located.

Glycosphingolipid receptors for anti-Gd and anti-p cold agglutinins

Anti-Gd and anti-p cold agglutinins exhibit similar serological properties: neuraminidase treatment of erythrocytes greatly reduces their agglutinability by these antibodies and protease treatment enhances their agglutination. We reported previously that an anti-p cold agglutinin was inhibited by sialosyllactoneotetraosylceramide, NeuAc(alpha 2-3)Gal(beta 1-4)GlcNAc(beta 1-3)Gal(beta 1-4)Glc-Cer, the most abundant ganglioside of human erythrocytes. We now report that two less abundant gangliosides are more potent inhibitors of this antibody, and of the anti-Gd antibodies, than sialosyllactoneotetraosylceramide. These two gangliosides have the same carbohydrate chain, NeuAc(alpha 2-3)Gal(beta 1-4)GlcNAc(beta 1-3)Gal(beta 1-4)GlcNAc(beta 1-3)Gal(beta 1-4)Glc(SNH), but they differ in their ceramide moiety. The principal fatty acid of SNH-1 is C16:0, whereas SNH-2 contains a predominance of C22:0, C24:0 and C24:1. No inhibition was produced by the ganglioside, NeuAc(alpha 2-6)Gal(beta 1-4)GlcNAc(beta 1-3)Gal(beta 1-4)Glc-Cer. Another monoclonal cold agglutinin, Sa, which shares some serological properties with anti-Gd cold agglutinins, was not inhibited by any of these gangliosides.

A new Pk phenotype in the P blood group system

A healthy 22-year-old woman was noted to have erythrocytes of the Pk phenotype: a strong Pk antigen, no detectable P antigen and anti-P antibody in her serum. Her erythrocytes contained four to six times as much Pk glycolipid (globotriaosylceramide or CTH) and approximately half as much P glycolipid (globotetraosylceramide or globoside) as normal red cells. The structures of CTH and globoside were characterized by analysis of permethylated sugars and complement fixation, in addition to chromatographic mobility and sugar composition. Inasmuch as the erythrocytes of two Pk individuals that were analysed previously (Marcus et al., 1976) contained no detectable globoside, these abnormalities appear to represent a new phenotype in the P blood group system.

DEAE-silica gel and DEAE-controlled porous glass as ion exchangers for isolation of glycolipids

DEAE-silica gel and DEAE-controlled porous glass have been used for the quantitative isolation of gangliosides and neutral glycosphingolipids from animal tissues and cells. A direct comparative study between DEAE-silica gel, DEAE-controlled porous glass and DEAE-Sephadex was made; the results indicated that DEAE-silica gel is preferable to the other two ion exchangers. DEAE-silica gel has also been found to be suitable for the fractionation of ganglioside mixtures.

Gangliosides and other lipid micelles. A study of amine binding by a dialysis/fluorescence method

The binding of serotonin to bovine adrenal medulla gangliosides (BAMG), bovine brain gangliosides (BBG), and BBG-synthetic lecithin mixed micelles has been demonstrated by a rapid technique using fluorescence monitoring of dialysis rates. BAMG micelles bound 0.10 mM serotonin at about half the efficiency of BBG micelles having the same sialic acid concentration (0.50 mM) in water. In water, the effect of BBG micelles was essentially identical to that of mixed micelles containing the same quantity of BBG. Ca2+ (1.20 mM), however, cancelled the effect of the mixed micelles on serotonin dialysis and reduced the effect of BBG micelles to about one quarter of that observed in water. These and other observations are related to earlier studies and to neurochemical processes which may involve gangliosides.

Blood-group-Ii-active gangliosides of human erythrocyte membranes

More than ten new types of gangliosides, in addition to haematoside and sialosylparagloboside, were isolated from human erythrocyte membranes. These were separated by successive chromatographies on DEAE-Sephadex, on porous silica-gel columns and on thin-layer silica gel as acetylated compounds. Highly potent blood-group-Ii and moderate blood-group-H activities were demonstrated in some of the ganglioside fractions. The gangliosides incorporated into cholesterol/phosphatidylcholine liposomes stoicheiometrically inhibited binding of anti-(blood-group I and i) antibodies to a radioiodinated blood-group-Ii-active glycoprotein. The fraction with the highest blood-group-I-activity, I(g) fraction, behaved like sialosyl-deca- to -dodeca-glycosylceramides on t.l.c. Certain blood-group-I and most of the -i determinants were in partially or completely cryptic form and could be unmasked by sialidase treatment. Thus the I and i antigens, which are known to occur on internal structures of blood-group-ABH-active glycoproteins in secretions, also occur in the interior of the carbohydrate chains of erythrocyte gangliosides.

Ganglioside structures and distribution: are they localized at the nerve ending?

Gangliosides generally provide a small portion of the complex carbohydrate content of cell surfaces. An exception is the central nervous system where they comprise up to 5--10% of the total lipid of some membranes. This tissue is unique in that the quantity of lipid-bound sialic acid exceeds that of the protein-bound fraction. Over 30 different molecular species have been characterized to date. These range in complexity from sialosylgalactosyl ceramide with 2 sugars to the pentasialoganglioside of fish brain with 9 carbohydrate units. Virtually all cellular and subcellular fractions of brain that have been carefully examined contain gangliosides to one degree or another, but the majority of brain ganglioside is located in the neurons. Their mode of distribution within the neuron has not been entirely clarified by subcellular studies. Calculations based on reported values for axon terminal density and synaptosomal ganglioside concentration in the rat reveal that nerve endings contribute less than 12% of total cerebral cortical ganglioside. It is concluded that the plasma membranes of neuronal processes contain most of the neuronal ganglioside. These and other considerations suggest the possibility that gangliosides may be distributed over the entire neuronal surface.

Gangliosides and phospholipids of the membranes from bovine adrenal medullary chromaffin granules

The lipid and ganglioside compositions of membranes of chromaffin granules isolated from bovine adrenal medulla have been investigated. The detailed lipid analysis revealed the presence of high levels of lysophosphatidylcholine, in agreement with previous studies, but also of sphingomyelin and plasmalogens. From these membranes, gangliosides have been extracted and separated by thin-layer chromatography and analysed. 95% of the total recovered gangliosides were hematosides (GM3), which migrated as three major species. Sugar analyses have been performed, as well as the fatty acid compositions. The three hematoside gangliosides appeared to differ on the basis of their fatty acid composition. Compared with the brain, chromaffin granule membranes showed a simple ganglioside composition, thus offering a good model for the study of the metabolism and the role of gangliosides. The simple ganglioside composition of chromaffin granule membranes has allowed us to state that there are 60 mol phospholipid and 30 mol cholesterol per mol ganglioside.