Structural features of the contact zones for heparan sulphate self-association

The self-association between heparan sulphate chains has been investigated by using heparan sulphate oligosaccharides for the competitive elution of [3H]heparan sulphate from heparan sulphate-agarose. Partial or complete periodate-oxidation followed by alkali-catalysed scission afforded oligomers having the general structure GlcN-(HexA-GlcN)n-R. Oligosaccharides with n greater than 5 were able to desorb bound heparan sulphate, provided that mixed or alternating arrangements of iduronate and glucuronate were present in these fragments. Longer fragments were more effective than shorter ones. The present results corroborate previous proposals that the highly copolymeric regions of heparan sulphate serve as contact zones for the chain-chain association.