In this reaction, all reactants and products are invisible. The heat being evolved is the clue that tells you a reaction is taking place. This is a good example of an exothermic reaction, a reaction in which heat is given off. A lot of reactions are exothermic.
Prothrombinase will cleave prothrombin to make thrombin and thrombin is the enzyme that cuts fibrinogen to make fibrin for clot formation [Blood Clotting: The Basics]. The platelet prothrombinase activity is the same as the activity on TP-bearing cells: itâs formed from Xa and membrane-bound Va.
prothrombin, a plasma protein that is converted to the active form, factor IIa, or thrombin, by cleavage. Thrombin then cleaves fibrinogen to its active form, fibrin. Factor II deficiency leads to hypoprothrombinemia. Also called factor II.