Abstract

The distribution of the heteropolysaccharide chains in the insoluble tissular network of the dogfish cornea was investigated. For this purpose, the corneas were extracted with a buffer solution composed of 1 M CaCl2, 0.05 M tris and 0.02 M citric acid to remove soluble proteins. The residual insoluble stroma was successively hydrolysed by collagenase and pronase. The glycopeptides obtained were separated by gel filtration and high voltage electrophoresis. Two types of sugar chains were detected:(a) polyosides composed of galactose, glucose, mannose, glucosamine, fucose, xylose and sialic acid, some of them at least linked to aspartic acid (type 1);(b) galactose or glucosidogalactose linked to hydroxylysine (type 2).For one heteropolysaccharide chain of type 1, 6 galactosidohydroxylysines and 4 glucosidogalactosidohydroxylysines were found.The insoluble stroma was submitted to a fractionated extraction procedure by trichloroacetic acid and water in order to remove all collagenous material. The residual structural glycoprotein exempt from hydroxyproline was hydrolysed by pronase and the glycopeptide fraction was isolated by exclusion chromatography and electrophoresis. A single major glycopeptide fraction of the type 1 containing galactose, glucose, mannose, xylose and glucosamine was obtained.This clear‐cut separation of the two types of glycopeptides by the tricholoroacetic acid treatment indicates that they are bound to different peptide chains: glycane of type 1 is bound to the peptide chain of structural glycoproteins (insoluble in hot trichloroacetic acid) and the glycane of type 2 is bound to the peptide chains of collagen (soluble in hot trichloroacetic acid).

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