Chondroitin 6-sulfate hexosamine

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. 

Coll. = collagen CS = chondroitin sulfate KS = keratan sulfate (calculated from glucosamine values) SA = sialic acid OP = other protein, calculated from total nitrogen - (collagen + hexosamine nitrogen). 

These materials are also called aminopolysaccharides by Kent (K15, K16) or mucopolyuronides by Blix (B22). They contain uronic (hexu-ronic) acid, usually n-glucuronic acid. Only one other uronic acid occurring together with n-glucuronic acid, namely t-iduronic acid, has been found in chondroitin sulfate B (dermatan). In addition to uronic acid, most of these materials, with the exception of hyaluronic acid, contain sulfates (in ester form). They also contain hexosamine as glucosamine or galactosamine, frequently in acetylated form. 

B. Heterozooglycans (heterozoopolysaccharides). Zoopolysaccharides which contain two or more types of monosaccharide, hexosamine, or uronic acid. (Examples Hyaluronic acid, chondroitin sulfate, heparin, blood-type polysaccharides, keratosulfate.)... 

There is a strong possibility that chondroitin sulfate may occur in mammalian tissues as a hybrid molecule containing both 4- and 6-sulfated hexosamine residues in the same molecule. Although a standard mixture of chondroitin 4-sulfate and chondroitin 6-suIfate may readily be separ... 

In the wmrk of Meezan and Davidson (1967b) the interesting observation was made that sulfate incorporated into protein-free chondroitin sulfate was located mostly in position 6 of the hexosamine moiety, whereas position 4 w as preferentially sulfated, when the protein portion of the molecule was intact. Although a ready explanation of this finding is currently not available, it may be hypothesized that the protein moiety influences the conformation of the protein polysaccharide in such a fashion as to make the hydroxyl groups in position 4 more accessible to sulfation. 

These properties for a few characterized hyaluronidases are summarized in Table V. It will be seen that with one exception, hyaluronidases act upon, both hyaluronate and chondroitin, so that they resemble the exohexosaminidases in their low specificity for the C-4 hexosamine configuration, but differ from them in that many hyaluronidases will attack 4-0- and 6-0-sulfated hexosamine moieties. 

A glycosaminoglycan is a heteropolysaccharide consisting of repeating disaccharide sequences, where each disaccharide contains a hexosamine and a hexuronic acid chondroitin sulfate, dermatan sulfate, heparin, and heparan sulfate). However, in keratan sulfate, the hexuronic acid moiety is replaced by a hexose [8, 28]. These... 

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