Chondroitin 6-sulfate glycosidic linkage

On the basis of the close correlation between the number of hydroxy-amino acids in bovine submaxillary mucin and the number of hexosamine and sialic acid residues, Hashimoto and Pigman (34) proposed that an O-glycosidic linkage was the only one that could be present in large amounts. Anderson et al. (38) reported a disappearance of much of the serine after incubation of the proteoglycan of chondroitin sulfate with alkali and suggested that this loss resulted from a -elimination reaction. 

The O-glycoside linkage between protein and carbohydrate exists in blood group substances and chondroitin sulfate. The others are N-asparaginyl linked. 

Hyaluronidase (HAase systematic name hyaluronate 4-glycanohydrolase EC 3.2.1.35) is a glycoside hydrolase that cleaves (l-4)-(i-N-acetylhexosaminide linkages in hyaluronan, chondroitin, chondroitin sulfate. 

Dermatan sulfate is an isomer of chondroitin 4-sulfate in which the D-glucuronic acid units have been replaced by L-iduronic acid units, the linkage positions and absolute orientations of the glycosidic linkages remaining the same. The repeating unit (V) is therefore 0-a-L-idopyra-nuronosyl-(l 3)-(2-acetamido-2-deoxy-0- -D-galactopyranosyl 4-sul-... 

In the natural state, the chains are often joined by glycosidic bonds to an L-serine residue of a polypeptide backbone. Other types of linkage also occur, as in keratan sulfate.84 It is not yet known whether hyaluronic acid is bound covalently to protein. The main part of each chain approximates to a regular alternation of residues of 2-acetamido-2-deoxy-D-hexose and of another sugar (often a uronic acid), but the sequence near the L-serine residues is different. In chondroitin 4-sulfate,85 it is ... 

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