- A key clot promoter, thrombin is an enzyme that presides over the conversion of a substance called fibrinogen to fibrin, the right stuff for a clot.
* * *1. An enzyme (proteinase), formed in shed blood, that converts fibrinogen into fibrin by hydrolyzing peptides (and amides and esters) of l-arginine; formed from prothrombin by the action of prothrombinase (factor Xa, another proteinase). 2. A sterile protein substance prepared from prothrombin of bovine origin through interaction with thromboplastin in the presence of calcium; causes clotting of whole blood, plasma, or a fibrinogen solution; used as a topical hemostatic for capillary bleeding with or without fibrin foam in general and plastic surgical procedures. SYN: factor IIa, fibrinogenase, thrombase, thrombosin.- human t. t. obtained from human plasma by precipitation with suitable salts and organic solvents; same uses as t..
* * *throm·bin 'thräm-bən n a proteolytic enzyme formed from prothrombin that facilitates the clotting of blood by catalyzing conversion of fibrinogen to fibrin and that is used in the form of a powder as a topical hemostatic called also thrombase
* * *n.a substance (coagulation factor) that acts as an enzyme, converting the soluble protein fibrinogen to the insoluble protein fibrin in the final stage of blood coagulation. Thrombin is not normally present in blood plasma, being derived from an inactive precursor, prothrombin.
* * *throm·bin (thromґbin) the activated form of coagulation factor II (prothrombin); it converts fibrinogen to fibrin. Called also fibrinogenase and thrombase. [USP] a sterile protein substance (topical t.) prepared from prothrombin of bovine origin through interaction with added thromboplastin in the presence of calcium; used therapeutically as a local hemostatic.
Medical dictionary. 2011.