The rate of the thrombin/antithrombin III reaction is determined with their molar ratio rather than their absolute concentrations.
A pico-molar concentration of thrombin was significantly inactivated by antithrombin III (AT III). The pseudo-first order rate constant, k'app, and the second order rate constant, k", were inversely proportional to the concentration of thrombin. The k'app and k" values increased and decreased, respectively, with increase in the concentration of AT III. All of these results indicated that the rate of the thrombin/AT III reaction was determined with the molar ratio of the two rather than their absolute concentrations.
D000818:Animals; D000990:Antithrombin III / Q000378:metabolism* / Q000494:pharmacology; D002417:Cattle; D066298:In Vitro Techniques; D007700:Kinetics; D013917:Thrombin / Q000037:antagonists & inhibitors / Q000378:metabolism*
D000990:Antithrombin III; D013917:Thrombin