Glycosaminoglycans (GAGs) including chondroitin sulfate (CS), dermatan sulfate, heparin, heparan sulfate and keratan sulfate (KS) are linear, sulfated repeating disaccharide sequences containing hexosamine and uronic acid (or galactose (Gal) in the case of KS). Among the GAGs, CS shows structural variations, such as sulfation patterns and fucosylation, which are responsible for their physiological functions through CS interaction with CS-binding proteins. Here, we solved the structure of KS-branched chondroitin sulfate E derived from a clam, Mactra chinensis. KS disaccharide [D-GlcNAc6S-(1→3)-β-D-Gal-(1→] was attached to the C-3 position of GlcA, and consecutive KS-branched disaccharide sequences were found in a CS chain. KS-branched polysaccharides clearly exhibited the resistance to degradation by chondroitinase ABC or ACII (at low concentrations) compared with typical CS structures. Furthermore, KS-branched polysaccharides stimulated neurite outgrowth of hippocampal neurons. These results strongly suggest that Mactra chinensis is a rich source of KS-branched CS and has important biological activities.
- chondroitin sulfate
- keratan sulfate
- ©2016 The Author(s)
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