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Sialyl-glycopeptides containing an O-glycosidically linked tetrasaccharide chain were obtained from the urine of a patient suffering from mucolipidosis I. Isolation of these compounds was achieved by gel filtration, ion-exchange chromatography and preparative paper chromatography. Their structures were determined by a combination of carbohydrate and amino acid analysis, dansylation, periodate oxidation, methylation studies, enzymatic hydrolysis and ¹H-NMR spectroscopy, to be as follows: ... wherein R = peptide linked through -Thr-, Ser-, -Ser-Thr- or -Thr-Ser-. The finding of these glycopeptides in urine shows that mucolipidosis I is characterized by a general "glycoprotein-specific" sialidase deficiency. The possibility of the existence of a human endo-α-N-acetylgalactosaminidase is discussed. [ABSTRACT FROM AUTHOR]

An immunoglobulin M from Waldenström's disease (IgM Ga) was hydrolysed by papain and a glycopeptide fraction was isolated by gel filtration on Sephadex G-100. This fraction was then successively resolved into fourteen glycopeptides by gel filtration on Sephadex G-50 and by preparative paper electrophoresis at pH 1.9. The amino acid and carbohydrate content of these glycopeptides was determined by ionexchange chromatography in an autoanalyzer. All of them contain aspartic acid and serine, but they are quite different from one another, in amino acid composition and sequence about, the carbohydrate-peptide linkage, especially with respect to histidine, tyrosine, threonine, valine, glutamic acid, lysine and proline. Furthermore, a number of glycopeptides contain only mannose and glucosamine, while others contain in addition, galactose, fucose, and N-acetylneuraminic acid, in variable amounts. These results suggest the presence of several linkage sites of the oligosaccharide chains on the H-chain and the true heterogeneity of these oligosaccharide chains. The peptide sequence of a few glyeopeptides was reported, especially the following: r-Asn(carbohydrates)-Ser-Thr, also present, in the Fc fragment of Immunoglobulin G. [ABSTRACT FROM AUTHOR]

The primary envelope gene product of the polycythemia-inducing strain of Friend spleen focus-forming virus, glycoprotein 52 (gp52), as well as its processed form, glycoprotein 65 (gp65), were isolated from virus- infected normal rat kidney cells metabolically labeled with [2-³H]mannose. Following digestion with trypsin, glycopeptides containing individual N-glycosylation sites were obtained by gel filtration and subsequent reversed-phase high-performance liquid chromatography. N- terminal amino acid sequencing of the glycopeptides demonstrated that only asparagine residues 11 and 26, located in the N-terminal domains of gp52 and gp65, carry carbohydrate substituents, while the potential N-glycosylation sites in the C-terminal portions of the molecules are not used. Carbohydrates attached were liberated by treatment with endo-β-N-acetylglucosaminidase H or peptide: N-glycosidase F and characterized by high-performance liquid chromatography. The results demonstrated that gp52 carries similar patterns of oligomannosidic glycans in both positions. In gp65, however, asparagine residue 11 is almost exclusively substituted by complete, fucosylated N- acetyllactosaminic oligosaccharides, whereas asparagine residue 26 carries oligomannosidic or truncated N-acetyllactosaminic glycans. [ABSTRACT FROM AUTHOR]

The asialoglycopeptides obtained from secretory immunoglobulins A from human milk have been separated by gel filtration and affinity chromatography on Concanavalin A-Sepharose and Lens culinaris agglutinin-Sepharose columns. Their structures have been determined by sugar analysis, methylation studies including mass spectrometry and 500-MHz 1H-NMR spectroscopy. The glycans are of the biantennary N-acetyllactosamine type differing in their degree of extension by fucosyl-N-acetyllactosamine residues. The overall structures of the glycopeptides are as follows: [This symbol cannot be presented in ASCII format] Most of the asialoglycopeptide structures possess an intersecting GlcNAc residue; they are suggested to be located on the alpha; chain of the secretory immunoglobulins A of human milk. The non-intersected structures probably occur on the secretory piece. The methodology applied to the structural analysis adequately coped with the extremely high degree of heterogeneity shown by the structures. [ABSTRACT FROM AUTHOR]

The glycopeptides containing either the disaccharide or the heteropolysaccharide chains were purified, after enzymatic digestion of glomerular basement-membrane antigens, by gel filtration and ion-exchange chromatography. Their antigenicity was investigated in seven patients with anti-glomerular-basement-membrane antibody-mediated glomerulonephritis, by the leukocyte migration test and radioimmunoassay. The leukocyte migration of the seven patients is inhibited in presence of membrane antigens with both types of oligosaccharide chains. The disaccharide-containing glycopeptide inhibits the leukocyte migration of these patients using 10-times less antigenic material; the heteropolysaccharide-containing glycopeptide does not modify the leukocyte migration of the same patients. Similarly, only the disaccharide-containing glycopeptide decreases the binding of labelled membrane antigens with anti-glomerular-basement-membrane antibodies, using the radioimmunoassay. This glycopeptide carries therefore the major antigenic determinants of humoral and cellular anti-basement-membrane auto-immunization. The amino acid sequence of the glycopeptide is Hyl-Gly-Glu-Asp-Gly the disaccharide prosthetic group being linked to the hydrolysine residue of the peptidic chain; its immunodominant antigenic site is formed by the Galp-Hyl unit. [ABSTRACT FROM AUTHOR]