Activation of factor X and thrombin zymogens in 25% sodium citrate solution
Journal
Thrombosis Research
Journal Volume
22
Journal Issue
1-2
Pages
203-212
Date Issued
1981
Author(s)
CHE-MING TENG
Abstract
No significant amounts of thrombin formed when purified prothrombin, prethrombin 1, or prethrombin 2 were separately dissolved in 25% sodium citrate solution even if purified thrombin was also added. Purified Factor X remained inactive but converted to Factor Xa when seeded with Factor Xa or thrombin. Autocatalysis occurs with Factor X. Mixtures of Factor X and prothrombin, Factor X and prethrombin 1, or Factor X and prethrombin 2, rapidly generated thrombin and β-Factor Xa. In the latter two combinations the process was accelerated by purified prothrombin fragment 2. Thrombin zymogens serve as substrates for Factor X and Factor X serves as a substrate for thrombin zymogens. This has been called reciprocal proenzyme activation. The zymogen is not as active with respect to itself as with respect to the other proenzyme. The old observation (Proc. Soc. Exp. Biol. Med. 72: 677-680 (1949)) is interpreted on the basis of reciprocal proenzyme activation, instead of autocatalysis of prothrombin. © 1981.
SDGs
Type
journal article