Thrombin


 * 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 pro-thrombin by the action of pro-thrombinase (factor Xa, another proteinase).
 * 2) a sterile protein substance prepared from pro-thrombin 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