Specificity of sulfated polysaccharides to accelerate the inhibition of activated protein C by protein C inhibitor.

The ability of various sulfated polysaccharides to activate protein C inhibitor (PCI) and the effect of molecular weight (Mr) and sulfur content of dextran sulfates were investigated. Besides dextran sulfate, highly sulfated polysaccharides such as chondroitin polysulfates 1 and 5, and pentosan polysulfate were more active than heparin in enhancing the activated protein C inhibition by PCI. The molecular weight and the sulfur content of dextran sulfate were critical for the second-order rate constant of the reaction and for the optimal concentration of the polysaccharide, respectively. These results suggest that the carboxyl groups of polysaccharides are not necessarily required, but some sulfate groups within polymers may play a critical role in the interaction with PCI.