Structure NeuAc Alpha Research Articles

One-Step Purification of an α(1-3)-L-Fucosyltransferase from Human Amniotic Fluid by Fetuin-Agarose Affinity Chromatography

A soluble alpha(1-3)-L-fucosyltransferase, which accepts carbohydrates of the general structure NeuAc alpha(2-3)Gal beta(1-4)GlcNAc beta-R as substrates and which is involved in the biosynthesis of the tumor-associated sialyl-LeX determinant, was purified about 125-fold from human amniotic fluid by a one-step affinity chromatography on fetuin-agarose. Upon SDS gel electrophoresis, the purified enzyme revealed a protein band with a relative molecular mass (Mr) of about 62,000. The enzyme acted equally well on sialoglycoproteins and their desialylated derivatives.

Biosynthesis of the cancer-associated sialyl-Lea antigen.

A cancer-associated glycolipid antigen defined by monoclonal antibody 19-9 has the structure NeuAc alpha 2-3Gal Gal beta 1-3GlcNAc beta 1-3Gal beta 1-4Glc beta 1-Cer. We have (formula; see text) studied its biosynthesis by testing the capacity of a crude microsomal fraction of SW 1116 cells to catalyze the addition of fucosyl or sialyl residues from GDP-fucose or CMP-sialic acid to glycolipid or oligosaccharide precursors. When the tetrasaccharide NeuAc alpha 2-3Gal beta 1-3GlcNAc beta 1-3Gal beta 1-4Glc (LSTa) is incubated with GDP-[14C]fucose and SW 1116 microsomes, a 14C-labeled oligosaccharide is formed that can be separated from the incubation mixture on an affinity column containing antibody 19-9 bound to protein A-Sepharose. The product migrates slower than LSTa when analyzed by paper or thin-layer chromatography. After treatment with neuraminidase, it co-migrates with the pentasaccharide Gal beta 1-3GlcNAc beta 1-3Gal beta 1-4Glc (formula; see text) (LNF II) in both chromatographic systems. Similar experiments demonstrate that SW 1116 microsomes catalyze the addition of a sialyl residue to the tetrasaccharide Gal beta 1-3GlcNAc beta 1-3Gal beta 1-4Glc to form LSTa. However, when LNF II is incubated with CMP-[14C]sialic acid and SW 1116 microsomes, no 19-9-active product is detected by affinity chromatography or by paper or thin-layer chromatography. Results using glycolipid precursors are consistent with these findings and also demonstrate the presence of the Lewis fucosyltransferase in SW 1116 cells. Thus, the biosynthesis of the sialyl-Lea antigen proceeds by addition of sialic acid to a type 1 precursor chain by a sialyltransferase, followed by addition of fucose by the Lewis fucosyltransferase.

Characterization of a human melanoma-associated ganglioside antigen defined by a monoclonal antibody, 4.2.

A monoclonal IgM antibody, 4.2, reacting with a surface antigen expressed on most human melanomas (Yeh, M.-I., Hellström, I., Abe, K., Hakomori, S., and Hellström, K. E. (1982) Int. J. Cancer, 29, 269-275) was shown to be directed to a ganglioside with the carbohydrate structure NeuAc alpha 2 leads to 8NeuAc alpha 2 leads to 3Gal beta 1 leads to 4Glc beta 1 leads to 1Cer. The carbohydrate structure, established by enzymatic degradation and methylation analysis with mass spectrometry, is identical with that of brain GD3 ganglioside, but its ceramide is characterized by a predominance of longer chain fatty acids, in contrast to brain GD3 that has mainly C18:0 fatty acid. The antibody did not react with various other gangliosides, including those having the same terminal sugar sequence (NeuAc alpha 2 leads to 8NeuAc alpha 2 leads to 3Gal) as GD3, such as GT1a and GQ1b. Its specificity is therefore restricted to the NeuAc alpha 2 leads to 8NeuAc alpha 2 leads to 3Gal beta 1 leads to 4Glc leads to Cer sequence, including the innermost sugar, Glc residue.

Isolation and structural characterization of human lymphocyte and neutrophil gangliosides.

Gangliosides were isolated from purified preparations of human peripheral blood lymphocytes and neutrophils. Structural analyses and comparisons were performed by direct probe mass spectrometry and by degradation studies with the following enzymes: Escherichia freundii endo-beta-galactosidase; Clostridium perfringens and Arthrobacter ureafaciens neuraminidase; and jack bean beta-N-acetylhexosaminidase and beta-galactosidase. This combination of techniques allowed us to obtain carbohydrate composition and sequence information without the aid of methylation or carbohydrate compositional analyses using only 1-2 mg of purified gangliosides. On the basis of these studies we propose that human lymphocytes and neutrophils have gangliosides with the following structures. NeuAc alpha 2 leads to 3Gal beta 1 leads to 4Glc beta 1 leads to 1Cer Structure A NeuAc alpha 2 leads to ? GlcNAc beta 1 leads to 3Gal beta 1 leads to 4Glc beta 1 leads to 1Cer Structure B NeuAc alpha 2 leads to ? Gal beta 1 leads to 3,4GlcNAc beta 1 leads to 3Gal beta 1 leads to 4Glc beta 1 leads to 1Cer Structure C All three compounds were isolated from both cell types with structure A being the major lymphocyte ganglioside and structure C the major neutrophil ganglioside. Structure B is a novel ganglioside and may represent a leukocyte-specific glycosphingolipid. Neuraminidase degradation studies demonstrated that only one ganglioside species of each cell type contains an internally linked sialic acid residue, and on the basis of thin layer chromatographic analysis this component is the same as the major brain ganglioside, GM1 (II3-N-acetylneuraminosyl-gangliotetraosylceramide). In addition, large gangliosides with the general structure NeuAc alpha 2 leads to ?(Gal beta 1 leads to 3,4GlcNAc beta 1 leads to 3)n Gal beta 1 leads to 4Glc beta 1 leads to 1Cer were isolated. These results are discussed as they relate to blood group antigens and specific cell surface markers in human leukocytes.

Sendai virus receptor: proposed recognition structure based on binding to plastic-adsorbed gangliosides.

The binding of Sendai virus to polystyrene petri dishes to which various gangliosides of defined structures had been adsorbed was determined. The ganglioside-bound virus was visualized either by a water vapor condensation method or by a hemadsorption method. By either assay, specific virus binding of high affinity was demonstrated to the gangliosides GT1a, GQ1b, and GPlc which have a common end sequence in the oligosaccharide moiety: NeuAc alpha 2 leads to 8NeuAc alpha 2 leads to 3Gal beta 1 leads to 3GalNAc leads to. Binding also occurred to the GD1a and GT1b gangliosides, which have the same end carbohydrate sequence except for the terminal N-acetylneuraminic acid, but the affinity was only 1-9% of that of the gangliosides with a terminal disialosyl linkage. It is proposed that the structure NeuAc alpha 2 leads to 8NeuAc alpha 2 leads to 3Gal beta 1 leads to 3GalNAc is the recognition-specific structure of the receptor for Sendai virus that is present on cell membrane gangliosides and possibly also glycoproteins. Binding tests to plastic-adsorbed glycolipids are suggested to be a useful tool for identification of the receptor recognition structure.