C. Orthner, S. Morris, D. Kosow
Sep 15, 1981
Citations
0
Influential Citations
3
Citations
Quality indicators
Journal
Thrombosis research
Abstract
Abstract The thrombin specific chromogenic substrates, Phe-Pipecolyl-Arg-p-nitroanilide (S-2238) and benzoyl-Phe-Val-Arg-p-nitroanilide (S-2160) are inhibitors of factor Xa amidolytic and proteolytic activity. The inhibition is of the partial noncompetitive type in that no change in the Km for the hydrolyzed substrate was observed and some factor Xa activity remains even at infinite inhibitor concentration. High performance liquid chromatographic analysis indicated that the inhibitors were essentially free of either p-nitroaniline or free peptide contamination. Neither p-nitroaniline nor acid hydrolyzed inhibitors were capable of inhibiting factor Xa demonstrating that a minimal peptide structure is necessary for inhibition. Our results indicate that factor Xa contains a regulatory site which, when occupied by certain peptides, causes a decrease in the rate of catalysis.