Glycopeptides des immunoglobulines.

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]