Partial activation of prothrombin and generation of prothrombin-R with cathepsin B

Abstract

Maximal yields of prothrombin-R were readily produced from a number of prothrombin derivatives when these were mixed with purified cathepsin B at pH 7.9. Thrombin was not a product when substrates prepared with either mitochondria or cathepsin B were used in the regeneration system. Conditions were found where the formation of prothrombin-R exhibited characteristics of either zero or first order kinetics with respect to the enzyme, cathepsin B. Iodoacetate partially or completely inhibited the formation of prothrombin-R. Various mechanisms which may account for the production of prothrombin-R are discussed.