A major heteropolysaccharide fraction was isolated from the 7S domain of human placental type IV collagen. Analyses revealed that it was an asparagine-linked oligosaccharide. Characterization using molecular sieve chromatography, exoglycosidase and endoglycosidase digestion, and chemical analysis suggested a bianternnary complex with the following structure:[Formula: see text]A microheterogeneity was noted with respect to the addition of the fucose and sialic acid residues. Analysis of component polypeptides of the 7S fraction following endoglycosidase treatment suggested that the most obvious site of heteropolysaccharide attachment was in a polypeptide of relative mass 40 000. Amino acid analysis of this isolated polypeptide indicated that it was rich in collagenous sequences and also contained half-cystine residues.
Purification and characterization of type IV collagen from mouse kidney.