Structure and anticoagulant activity of a fucosylated chondroitin sulfate from echinoderm. Sulfated fucose branches on the polysaccharide account for its high anticoagulant action.

A polysaccharide isolated from the body wall of the sea cucumber Ludwigothurea grisea has a backbone like that of mammalian chondroitin sulfate: [4-beta-D-GlcA-1-->3-beta-D-GalNAc-1]n but substituted at the 3-position of the beta--glucuronic acid residues with sulfated alpha--fucopyranosyl branches (Vieira, R. P., Mulloy, B., and Mourão, P. A. S. (1991) J. Biol. Chem. 266, 13530-13536). Mild acid hydrolysis removes the sulfated alpha--fucose branches, and cleaved residues have been characterized by 1H NMR spectroscopy; the most abundant species is fucose 4-O-monosulfate, but 2,4- and 3, 4-di-O-sulfated residues are also present. Degradation of the remaining polysaccharide with chondroitin ABC lyase shows that the sulfated alpha-L-fucose residues released by mild acid hydrolysis are concentrated toward the non-reducing end of the polysaccharide chains; enzyme-resistant polysaccharide material includes the reducing terminal and carries acid-resistant -fucose substitution. The sulfated alpha-L-fucose branches confer anticoagulant activity on the polysaccharide. The specific activity of fucosylated chondroitin sulfate in the activated partial thromboplastin time assay is greater than that of a linear homopolymeric alpha-L-fucan with about the same level of sulfation; this activity is lost on defucosylation or desulfation but not on carboxyl-reduction of the polymer. Assays with purified reagents show that the fucosylated chondroitin sulfate can potentiate the thrombin inhibition activity of both antithrombin and heparin cofactor II.