On the structure of cytolipin R, a ceramide tetrahexoside hapten from rat lymphosarcoma

Cytolipin R, a ceramide tetrahexoside isolated from rat lymphosarcoma, was studied by sequential hydrolysis with specific glycosidases which revealed the anomeric configurations of the glycosidic bonds. Sugar linkages were established by combined gas-liquid chromatography and mass spectrometry of the partially methylated alditol acetates prepared after permethylation and hydrolysis of the intact lipid. Results indicated the structure of cytolipin R to be N-acetylgalactosaminyl(beta1-->3)galactosyl(alpha1-->3) galactosyl(beta1-->4)glucosyl ceramide. Cytolipin K (globoside I) differs in having a -galactosyl(alpha1-->4)galactosyl- internal linkage, and this difference must account for the immunological differences between cytolipin K and cytolipin R.     

Effects of Divalent Cations on the Glycolipids from Cultured Mouse Neuroblastoma Cells

Abstract: The influence of divalent cations on glycosphingolipid metabolism was examined in the NB41A mouse neuroblastoma clonal cell line. HPLC methods were utilized to quantitate the effects on neutral glycolipids and monosialogangliosides. NB41A cells were shown to contain G_M3, G_M2, G_M1, G_D3, and G_D1a by HPLC and TLC. The neutral glycosphingolipids consisted of glucosylceramide (GlcCer), lactosylceramide (LacCer), GaINAc(β1→4) Gal(β1→4)Glc(β1→1)Cer (GgOse₃Cer), and GaINAc(β1→3)Gal(α1→4) Gal-(β1→4)Glc(β1→1)Cer (GbOse₃Cer) according to their HPLC behavior. Cells grown in the presence of 1.85 mm -EGTA showed a two- to threefold increase in G_M3 whereas other glycosphingolipids were only slightly affected. When cells were grown in the presence of 1.45 mm -EGTA plus 0.4 mm -EDTA a similar increase in G_M3 was observed but this change was now accompanied by decreases in G_M2, G_M1 GgOse₃Cer, and GbOse₄Cer. The EGTA-EDTA effects were reversed when growth was in the presence of Ca²⁺ sufficient to bind all chelator. Mn²⁺ replacement reversed the chelator effects differentially; G_M2 and G_M1 levels were the most sensitive to increases in Mn²⁺ concentration; GgOse₃Cer and GbOse₄Cer were also sensitive, whereas G_M3 was the least affected. These results suggest calcium serves an important regulatory role on G_M3 levels and that manganese concentration may regulate the levels of galactosamine-containing glycolipids in mouse NB41A neuroblastoma cells.     

OLIGOSACCHARIDE STORAGE IN BRAINS FROM PATIENTS WITH FUCOSIDOSIS,GM1-GANGLIOSIDOSIS AND GM2-GANGLIOSIDOSIS (SANDHOFF'S DISEASE)1

Abstract— Analysis of whole autopsy brain from a patient with fucosidosis (α-fucosidase deficiency) revealed minor storage of H-antigen glycolipid [Fuc (α, 1→2) Gal-GlcNAc-Gal-Glc-Ceramide] and a slightly abnormal ganglioside composition in the form of a two-fold elevation of G_M1 and the presence of a fucose-containing glycolipid (a minor component) which co-migrated with G_D1a. The major storage materials in fucosidosis brain were an oligosaccharide (Fuc-Gal-GlcNAc-Man[Fuc-Gal-GlcNAc-Man]-ManGlcNAc) and a disaccharide [Fuc(α, 1→6)-GlcNAc] in the approximate ratio of 5:1. Lesser amounts of a related oligosaccharide (Gal-GlcNAc-Man[Gal-GlcNAc-Man]-Man-GlcNAc) were isolated from the brain of patients with G_M1-gangliosidosis (Types I and II) where the major storage material is known to be G_M1-ganglioside (Gal (β, 1→3)GalNAc(β, 1→4) [NeuNAcf(α, 2→3) Gal(β, 1→4)Glc-Ceramide). Similarly, a related oligosaccharide (GlcNAc-Man [GlcNAc-Man]-Man-GlcNAc) was isolated from the brain of a patient with a total deficiency of N-acetyl-β-d -hexosaminidase (Sandhoff variant of G_M2-gangliosidosis) where the major storage products are known to be G_M2-ganglioside (GalNAc (β 1→4) [NeuNAc (α, 2→3)Gal(β, 1→4)Glc-Ceramine) and its asialo derivative. These studies indicate that glycoproteins containing at least 2 mol of l -fucose per oligosaccharide unit are normally catabolized in human brain. Further, it appears that such glycoproteins are initially catabolized by an endo-N-acetylglucosaminidase to release an oligosaccharide which is then degraded by the sequential action of exo-glycosidases.     

Characterization of major glycolipids in bovine erythrocyte membrane

Several neutral glycolipids and gangliosides were isolated from bovine erythrocyte stroma. Their structures were determined by partial acid hydrolysis, methylation analysis, periodate oxidation and CrO3 oxidation. Two major neutral glycolipids were characterized as lactosylceramide and galactosyl(alpha1--3)galactosyl(beta1--4)N-acetylglucosaminyl(beta1--3)galactosyl(beta1--4)glucosyl(beta1--1)ceramide. Two major gangliosides were N-glycolylneuraminosyl(2--3)galactosyl(beta1--4)glucosyl(beta1--1)ceramide and N-glycolylneuraminosyl(2--3)galactosyl(beta1--4)N-acetylglucosaminyl(beta1--3)galactosyl(beta1--4)glucosyl(beta1--1)ceramide. Minor glycolipids were glucosyl- and galactosylceramide, glucosamine-containing tri- and tetraglycosylceramide, glucosamine-containing disialosylhexaglycosylceramide, and gangliosides containing N-acetylneuraminic acid. The ceramide moiety of each glycolipid contained perdominantly d18:1 sphingosine, and normal fatty acids of C16:0, C22:0, C24:0, and C24:1.     

Synthesis of blockwise alkylated (1→4) linked trisaccharides as surfactants: influence of configuration of anomeric position on their surface activities

New carbohydrate-based surfactants consisting of hydrophilic cellobiosyl and hydrophobic glucosyl residues, methyl β-d-glucopyranosyl-(1→4)-α-d-glucopyranosyl-(1→4)-2,3,6-tri-O-methyl-α-d-glucopyranoside 1 (GβGαMα, G: glucopyranosyl residue, α and β: α-(1→4)- and β-(1→4) glycosidic bonds, M: methyl group), 2 (G_βG_βM_α), 3 (G_βG_αM_β), 4 (G_βG_βM_β), 5 (G_βG_αE_α, E: ethyl group), 6 (G_βG_βE_α), 7 (G_βG_αE_β), 8 (G_βG_βE_β) and eight α-and β-glycoside mixtures (a mixture of 1 and 2: 1/2 = 62/38 (9), 32/68 (10); a mixture of 3 and 4: 3/4 = 69/31 (11), 32/68 (12); a mixture of 5 and 6: 5/6 = 62/38 (13), 33/67 (14); a mixture of 7 and 8: 7/8 = 59/41 (15), 29/71 (16)) were synthesized via combined methods consisting of acid-catalyzed alcoholysis of cellulose ethers and glycosylation of phenyl thio-cellobioside derivatives. Their surface activities in aqueous solution depended on their chemical structures: α- or β-(1→4) linkage between hydrophilic cellobiosyl and hydrophobic glucosyl blocks, methyl or ethyl groups of hydrophobic glucosyl block, and α- or β-linked ether group at the C-1 of hydrophobic glucosyl block. The mixing effect of α- and β-glycosides on surface activities was also investigated. As a result, ethyl β-d-glucopyranosyl-(1→4)-α-d-glucopyranosyl-(1→4)-2,3,6-tri-O-ethyl-β-d-glucopyranoside 7 (G_βG_αE_β) had the highest surface activity, and its critical micellar concentration (CMC) and γ_CMC (surface tension at CMC) values of compound 7 were 0.5 mM (ca. 0.03 wt %) and 34.5 mN/m, respectively. The surface tensions of α- and β-glycoside mixtures except for compounds 9 and 10 were almost equal to those of pure compounds. The syntheses of the mixtures of α- and β-glycosides without purification process are easier than those of pure compounds. Thus, the mixtures should be more practical compounds for industrial use as a surfactant.     

Structural and compositional difference in the neutral glycolipids between epithelial and non-epithelial tissue of the mouse small intestine

Five major neutral glycolipids, GL-1-GL-5, were isolated from the the mouse small intestine. Their structures and distribution were determined by permethylation analysis, sequential degradation with exoglycosidases and/or immunohistochemistry. The molar ratio of GL-1, GL-2, GL-3, GL-4 and Gl-5 in the whole small intestine was 1:0.04:0.03:0.42:0.02. The structures of GL-1 and GL-4 present in epithelial cells were reported previously to be glucosyl ceramide and asialo G_M1, respectively (Umesaki, Y., Suzuki, A., Kasama, T., Tohyama, K., Mutai, M. and Yamakawa, T. (1981) J. Biochem. 90, 1731–1738). GL-5, also present in the epithelial cells, was fucosyl asialo G_M1, and fucose was shown to be linked to terminal galactose of asialo G_M1 in the manner of α(1–2) bond. GL-2 and GL-3, present in the residual tissue after scraping the mucosa, were determined to be globoside and Forssman glycolipid, respectively. Both globoside and Forssman glycolipid of the non-epithelial tissue had non-hydroxy fatty acid (C₁₆–C₂₄) in combination with sphingosine (C₁₈) as the ceramide components, in contrast with the ceramide structures of the epithelial glycolipids, which contained α-hydroxy fatty acids in combination with phytosphingosine. Immunohistochemical staining using anti-glycolipid antibodies confirmed the distribution of asialo G_M1 and fucosyl asialo G_M1, and Forssman glycolipid in the epithelial and non-epithelial tissue, respectively.     

猴头菌水溶性多糖的分离纯化与结构表征

从猴头菌子实体中分离得到一种新型的水溶性杂多糖HEPF2,分子量大小为1.66′104Da,该多糖由岩藻糖、半乳糖和葡萄糖以1.00:3.69:5.42比例构成,同时也含有微量的3-O-甲基鼠李糖。进一步利用傅立叶变换红外光谱法、糖组成分析、甲基化分析、部分酸水解法和核磁共振法等方法进行结构鉴定,检测结果表明,该杂多糖中包含1→4、1→6结合的葡萄糖和1→6结合的半乳糖残基,连接于主链的侧链残基,包括岩藻糖残基、少数的端基葡萄糖和半乳糖残基。核磁共振法检测结果还表明,1→4结合葡萄糖为β构型,(1→6)结合半乳糖、(1→2,6)结合半乳糖和端基葡萄糖均为α构型。     

Preparation and characterization of antibody to galactosyl(α1 → 4)galactosyl(β1 → 4)glucosylceramide

Antiserum against galactosyl(α1 → 4)galactosyl(β1 → 4)glucosylceramide (globotriaosylceramide, Gb₃) was raised in rabbits by the administration of four weekly intramuscular injections of 1.5 mg of the purified glycolipid along with bovine serum albumin and Freund's complete adjuvant. AntiGb₃ activity was quantitated initially by immunoprecipitation employing Gb₃ mixed with 100-fold excess of lecithin and cholesterol (1 : 1 or 1 : 2, by wt.) as antigen. Subsequently, complement fixation tests done with antigen preparations containing Gb₃/lecithin/cholesterol (1 : 6 : 20, by wt.) showed antiGb₃ titres of up to 1 : 8192. Fractionation of the antiserum by BioGel A5m chromatography indicated the antibody was an IgM immunoglobulin. The partially purified antibody stimulated complement-dependent release of glucose from glucose-containing liposomes prepared with sphingomyelin/cholesterol/dicetylphosphate/Gb₃ (molar ratio, 100 : 75 : 11 : 1). The antibody crossreacted with the trisaccharide, Gal(α1 → 4)Gal(β1 → 4)Glc, but not with galactosylceramide, lactosylceramide, GM1 ganglioside, globotetraosylceramide, digalactosyldiglyceride or a number of low molecular weight saccharides.     

The structure of canine intestinal trihexosylceramide

One of the neutral glycosphingolipids isolated from dog intestine has a mobility on thin-layer chromatography and a carbohydrate composition similar to trihexosylceramides. Structural analysis has shown that it consists largely of isoglobotriaosylceramide, galactosyl(alpha-1-3)galactosyl(beta-1-4)glucosyl(beta 1-1')ceramide.     

Synthesis of blockwise alkylated (1→4) linked trisaccharides as surfactants: influence of configuration of anomeric position on their surface activities

New carbohydrate-based surfactants consisting of hydrophilic cellobiosyl and hydrophobic glucosyl residues, methyl β-d-glucopyranosyl-(1→4)-α-d-glucopyranosyl-(1→4)-2,3,6-tri-O-methyl-α-d-glucopyranoside 1 (GβGαMα, G: glucopyranosyl residue, α and β: α-(1→4)- and β-(1→4) glycosidic bonds, M: methyl group), 2 (G(β)G(β)M(α)), 3 (G(β)G(α)M(β)), 4 (G(β)G(β)M(β)), 5 (G(β)G(α)E(α), E: ethyl group), 6 (G(β)G(β)E(α)), 7 (G(β)G(α)E(β)), 8 (G(β)G(β)E(β)) and eight α-and β-glycoside mixtures (a mixture of 1 and 2: 1/2=62/38 (9), 32/68 (10); a mixture of 3 and 4: 3/4=69/31 (11), 32/68 (12); a mixture of 5 and 6: 5/6=62/38 (13), 33/67 (14); a mixture of 7 and 8: 7/8=59/41 (15), 29/71 (16)) were synthesized via combined methods consisting of acid-catalyzed alcoholysis of cellulose ethers and glycosylation of phenyl thio-cellobioside derivatives. Their surface activities in aqueous solution depended on their chemical structures: α- or β-(1→4) linkage between hydrophilic cellobiosyl and hydrophobic glucosyl blocks, methyl or ethyl groups of hydrophobic glucosyl block, and α- or β-linked ether group at the C-1 of hydrophobic glucosyl block. The mixing effect of α- and β-glycosides on surface activities was also investigated. As a result, ethyl β-d-glucopyranosyl-(1→4)-α-d-glucopyranosyl-(1→4)-2,3,6-tri-O-ethyl-β-d-glucopyranoside 7 (G(β)G(α)E(β)) had the highest surface activity, and its critical micellar concentration (CMC) and γ(CMC) (surface tension at CMC) values of compound 7 were 0.5mM (ca. 0.03wt%) and 34.5mN/m, respectively. The surface tensions of α- and β-glycoside mixtures except for compounds 9 and 10 were almost equal to those of pure compounds. The syntheses of the mixtures of α- and β-glycosides without purification process are easier than those of pure compounds. Thus, the mixtures should be more practical compounds for industrial use as a surfactant.     

Molecular Species of Ceramide and Mono-, Di-, Tri-, and Tetraglycosylceramide in Bran and Endosperm of Rice Grains

Ceramide and mono-, di-, tri-, and tetraglycosylceramide were isolated from the bran and endosperm of rice grains and chemically characterized. The detailed compositions of free ceramide were somewhat different between the bran and endosperm, but those of the ceramide moiety in glycosylceramides were substantially the same. There was a tendency in all the sphingolipid molecules in rice grains for hydroxy acids with C₂₀ to be combined largely with the dihydroxy bases while hydroxy acids with C_24< combined mainly with the trihydroxy bases. Representative molecular species of the sphingolipid classes were concluded to be as follows: for ceramide N-2′-hydroxylignoceroyl-4-hydroxysphinganine, for monoglycosylceramide l-O-β-glucosyl-N-2′-hydroxyarachidoyl-4,8-sphingadienine, for diglycosylceramide 1-O-[β-mannosyl(1→-4)-O-β-glucosyl]- and 1-O-[β-glucosyl(1→4)-O-β-glucosyl]-N-2′-hydroxylignoceroyl-4-hydroxy-8-sphingenine, for triglycosylceramide l-O-[β-mannosyl(1→4)-O-β-mannosyl(l→4)-O-β-glucosyl]- and l-O-[β-glucosyl(l→4)-O-β-mannosyl(1→4)-O-β-glucosyl]-N-2′-hydroxylignoceroyl-4-hydroxy-8-sphingenine, and for tetraglycosylceramide 1-0-[β-mannosyl(l→4)-O-β-mannosyl (1→4)-O-β-mannosyl(1→4)-O-β-glucosyl]- and l-O-[β-glucosyl(1→4)-O-β-mannosyl(l→4)-O-β-mannosyl(1β4)-O-β-glucosyl]-N-2′-hydroxylignoceroyl-4-hydroxy-8-sphingenine.     

Structure of the major gangliosides from bovine thyroid.

After preparative isolation, the carbohydrate, long chain base, and fatty acid composition of the major gangliosides from bovine thyroid have been analyzed. The structures were elucidated by determining the molar ratio of the building blocks, permethylation analysis, and enzymatic degradation studies. The following structures are identified: N-Acetylneuraminyl(2,3)-galactosyl(1,4)glucosyl(1,1)ceramidie; N-glycolyneuraminyl(2,3)galactosyl(1,4)glucosyl(1,1)ceramide; galactosyl(1,3)N-acetylgalactosaminyl[(3,2)N-acetylneuraminyl](1,4)galactosyl(1,4)glucosyl(1,1)ceramide; fucosyl(1,2)galactosyl(1,3)N-acetylgalactosaminyl[(3,2)N-acetylneuraminyl](1,4)galactosyl(1,4)glucosyl(1,1)-ceramide. The structures were confirmed by direct inlet mass spectrometry of the permethylated gangliosides and the corresponding asialo derivatives. Structures are proposed for common ions in the different mass spectra.     

SPHINGOGLYCOLIPIDS IN THE NERVOUS SYSTEM IN FABRY'S DISEASE

Abstract— Two glycolipids, accumulated in the spinal ganglia of a patient with Fabry's disease were identified as: galactosyl (α1 → 4) galactosyl (β1 → 4) glucosyl(1 → 1) ceramide (CTH) and galactosyl (α1 → 4) galactosyl(1 → 1) ceramide (CDG). Only one glycolipid which had the same structure as the CTH in the spinal ganglia accumulated in the sympathetic ganglia of the patient. In the nervous system, CTH contained behenic acid (C_22:0) as the major fatty acid. In the spinal ganglia, CDG also contained behenic acid as the major fatty acid.     

Metabolism of GM1 ganglioside in cultured skin fibroblasts: anomalies in gangliosidoses,sialidoses, and sphingolipid activator protein (SAP,saposin) 1 and prosaposin deficient disorders

Summary Cultured skin fibroblasts from controls and patients with lysosomal storage diseases were loaded with G_M1 ganglioside that had been labelled with tritium in its ceramide moiety. After a 65-h or 240-h incubation, a large percentage of this ganglioside remained undegraded in G_M1 gangliosidoses, whereas in the other storage diseases studied, one of its metabolites accumulated by 2–4 fold relative to controls. Labelled G_M2 ganglioside accumulated in 4 variants of G_M2 gangliosidosis, whereas labelled G_M3 ganglioside accumulated in sialidosis, galactosialidoses and sphingolipid activator protein 1 (SAP-1, saposin B) and prosaposin (saposin A, B, C an D) deficient lipidoses. The reduced degradation of G_M3 ganglioside in the SAP-1 and prosaposin deficiencies was attributed to the deficient function of SAP-1. The prosaposin deficient cells also showed a reduced re-utilization of radioactive metabolites from G_M1 ganglioside (i.e. sphingosine and fatty acid) for phospholipid biosynthesis compared with fibroblasts from the SAP-1 deficient patient or normal controls. This anomaly was ascribed to the previously shown defect in ceramide degradation in prosaposin deficiency.     

Structure and Taste of Some Analogs of Naringin

The structures of acidic oligosaccharides synthesized by a transglycosylation reaction by Bacillus circulans β-galactosidase, using lactose as the galactosyl donor, and N-acetylneuraminic acid (NeuAc) and glucuronic acid (GlcUA) as the acceptors were investigated. Acidic oligosaccharides thus synthesized were purified by anion exchange chromatography and charcoal chromatography. The MS and NMR studies indicated that the acidic oligosaccharides from NeuAc were Galβ-(1→8)-NeuAc, Galβ-(1→9)-NeuAc, and Galβ-(1→3)-Galβ-(1→8)-NeuAc, and those from GlcUA were Galβ-(1→3)-GlcUA and Galβ-(1→4)-Galβ-(1→3)-GlcUA. These are novel acidic galactooligosaccharides.     

Chemical structure of monosialoganglioside GM1b biosynthesized in vitro.

The structure of a neuraminidase-labile monosialoganglioside which is formed in vivo from asialoganglioside (galactosyl (beta, 1 in equilibrium 3) N-acetylgalactosaminyl (beta, 1 in equilibrium 4) galactosyl (beta, 1 in equilibrium 4) glucosyl (1 in equilibrium 1) ceramide) and cytidine-5'-monophospho-N-acetylneuraminic acid in the presence of young rat brain sialytransferase has been established. This monosialoganglioside contains a neuraminidase-labile N-acetylneuraminyl group which is linked at position C-3 of the terminal galactosyl unit. This result was obtained by ultramicro scale permethylation of radioactive neuraminidase-labile monosialoganglioside biosynthesized from asialoganglioside labeled with tritium in the terminal galactose.     

Human erythrocyte P and Pk blood group antigens: identification as glycosphingolipids

The human erythrocyte P blood group system consists of three known antigens, P₁, P and P^k. We have identified the P antigen as the glycosphingo-lipid globoside, βGalNAc(1→3)αGal(1→4)βGal(1→4)Glc-cer, and the P^k antigen as ceramide trihexoside, αGal(1→4)βGal(1→4)Glc-cer. These data suggest, in contrast to previous hypotheses, that the P^k antigen is a biosynthetic precursor of P, and that neither P nor P^k is a precursor of P₁. These findings also provide an explanation for the apparent recessive inheritance of the P^k antigen, and for the nature of the biochemical abnormality in individuals of the rare P^k and p phenotypes.     

Halorussus rarus gen. nov., sp. nov., a new member of the family Halobacteriaceae isolated from a marine solar saltern

Two halophilic archaeal strains TBN4^T and TBN5 were isolated from Taibei marine solar saltern in Jiangsu, China. Both strains showed light red-pigmented colonies and their cells were rod, motile and Gram-stain-negative. They were able to grow at 25–50°C (optimum 37°C), at 1.4–4.3 M NaCl (optimum 2.1 M NaCl), at 0–1.0 M MgCl₂ (optimum 0.005 M MgCl₂) and at pH 6.0–9.0 (optimum pH 7.0). Their cells lyse in distilled water and minimal NaCl concentration to prevent cell lysis is 8% (w/v). The major polar lipids of the two strains were PG (phosphatidylglycerol), PGP-Me (phosphatidylglycerol phosphate methyl ester), PGS (phosphatidylglycerol sulfate) and five glycolipids chromatographically identical to S-TGD-1 (sulfated galactosyl mannosyl glucosyl diether), S-DGD-1 (sulfated mannosyl glucosyl diether), TGD-1 (galactosyl mannosyl glucosyl diether), DGD-1 (mannosyl glucosyl diether) and DGD-2 (an unknown diglycosyl diether). Phylogenetic analysis revealed that TBN4^T and strain TBN5 formed a distinct clade with genus Haladaptatus (showing 90.0–90.9% 16S rRNA gene similarities). The DNA G + C content of strain TBN4^T and strain TBN5 are 66.1 and 65.4 mol%, respectively. The DNA–DNA hybridization value between strain TBN4^T and strain TBN5 was 94.3%. The phenotypic, chemotaxonomic and phylogenetic properties suggest that strain TBN4^T and strain TBN5 represent a novel species in a new genus within the family Halobacteriaceae, for which the name Halorussus rarus gen. nov., sp. nov. is proposed. The type strain is TBN4^T (=CGMCC 1.10122^T = JCM 16429^T).     

The common structure in fucosyllactosaminolipids accumulating in human adenocarcinomas,and its possible absence in normal tissue

Two major glycolipids accumulating in a human primary liver adenocarcinoma, but absent in normal liver, were characterized as lacto-N-fucopentaosyl(III)ceramide and difucosyllacto-N-$\text{nor}$-hexaosylceramide, (Galβ1→4[Fucα1→3]GlcNAcβ1→3Galβ1→4[Fucα1→3]GlcNAcβ1→3Galβ1→4Glcβ1→1Cer), a new type of glycolipid with Le^x-determinant. Comparison of glycolipids bearing Le^x-determinant in various cases of human colonic adenocarcinoma, in adjacent normal mucosa tissue, and in erythrocytes reveals a possibility that glycolipids accumulating in human adenocarcinoma, but not in normal tissue, have a common structural unit as identified below:

     

Interconversion of the A and B forms of ceramide trihexosidase from human plasma

The human plasma α-galactosidases which specifically hydrolyze galactosyl-(α1→4)galactosyl(β1→ 4)glucosylceramide consist of an A group with optimal enzymatic activity at pH 5.4, and a B group, which is characterized by optimal activity at pH 7.2. The relationship between the A and B groups of these α-galactosidases (ceramide trihexosidases) has been investigated with regard to their sialic acid content. Partial neuraminidase treatment of the most acidic (A-1) form of ceramide trihexosidase yields a complex mixture of 14 enzymatically active proteins separable by isoelectric focusing. Exposure to neuraminidase for a longer time causes an almost complete conversion of the A-1 form to a protein which has the same electrophoretic properties as the least acidic (B-V) form. Conversely, a crude kidney sialyltransferase preparation can be used to incorporate either CMP[1-¹⁴C]sialic acid or UDP-N-acetyl[1-¹⁴C]glucosamine into the B-V form of the enzyme. Sialyltransferase treatment causes the formation of a complex mixture of enzymatically active proteins, one of which has the same electrophoretic characteristics as the A-1 and A-2 forms of ceramide trihexosidase. On the basis of these studies it is suggested that the multiple forms of plasma ceramide trihexosidase are glycoproteins which differ primarily in their sialic acid content.