title: Self-damping mechanism in blood coagulation.
abstract: Two reactions of the extrinsic pathway of coagulation, the activations of Factor X and prothrombin, have been studied in purified systems and shown to be self-damping. Factor X was activated by the tissue factor-Factor VII complex, and prothrombin by two systems: the coagulant protein of Taipan venom, and the physiological complex of activated Factor X, Factor V, lipid, and calcium ions. In each case the yield of enzyme, activated Factor X or thrombin, is a function of the concentration of activator. These and other observations are considered as a basis for a control mechanism in coagulation.
mesh_terms: D001777:Blood Coagulation; D003067:Coenzymes; D004789:Enzyme Activation; D005164:Factor IX / Q000502:physiology; D005165:Factor V / Q000502:physiology; D005167:Factor VII / Q000502:physiology; D005169:Factor VIII / Q000502:physiology; D005170:Factor X / Q000502:physiology; D005246:Feedback; D007700:Kinetics; D011516:Prothrombin / Q000502:physiology
chemical_list: D003067:Coenzymes; D005165:Factor V; D005167:Factor VII; D011516:Prothrombin; D005169:Factor VIII; D005164:Factor IX; D005170:Factor X