PMID: 2500433Jul 5, 1989Paper

Molecular recognition in the activation of human blood coagulation factor X

The Journal of Biological Chemistry
A Chattopadhyay, D S Fair

Abstract

Factor X can be activated by the extrinsic activation complex (factor VIIa:tissue factor), the intrinsic activation complex (factor IXa:factor VIIIa) and by an enzyme from Russell's viper venom (RVV-X). To identify the regions on the surface of factor X that mediate its association with these three activators, we have prepared 21 synthetic peptides representing 65% of the primary structure of factor X. Only 3 of the 21 peptides inhibited the rate of factor X activation, indicating the regions represented by these three peptides are involved in factor X association. Using purified components, the rate of factor Xa formation was inhibited in a dose-dependent manner by these three peptides with the same relative potency of inhibition in each of the activation systems. The observed relative potencies were: peptide 267-283 greater than or equal to peptide 284-303 greater than peptide 417-431. Kinetic analyses indicated that the three peptides inhibited factor X activation in a non-competitive manner, and in mixed inhibitor assays the peptides were shown to be mutually exclusive of one another. In coagulation-based assays, the potency of inhibition by each peptide was decreased. However, in Russell's viper venom-X-initiated assays pe...Continue Reading

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