The interaction of glycosaminoglycans with heparin cofactor II: structure and activity of a high-affinity dermatan sulfate hexasaccharide.

The binding sites for dermatan sulfate and heparin in HCII overlap but are not identical. This may explain the observation that HCII binds non-specifically to heparin oligosaccharides but preferentially binds to a minor hexasaccharide isolated from dermatan sulfate having the structure shown in Fig. 4B. The tissue distribution of dermatan sulfate molecules containing the high-affinity HCII binding site may regulate HCII activity in vivo. Finally, in the presence of dermatan sulfate or heparin, the N-terminal acidic domain of HCII may interact with the hirudin-binding site of thrombin to produce maximal stimulation of the thrombin-HCII reaction.