Coagulation and its cascade
Hemostasis is controlled by the formation of thrombin (factor IIa) the enzyme which converts fibrinogen into fibrin. Thrombin itself is formed from prothrombin (factor II) at the end of the coagulation cascade. The biochemical properties of the coagulation factors can be grouped as follows: Factors II, VII, IX, X, XI and XII are all pro-enzymes. The so called vitamin K dependent factors (factors II, VII, IX and X) contain 10-12 γ-carboxyglutamic acid residues (Gla’s) in the aminoterminal end of the protein, which defines their affinity for phospholipid membranes. Factors V and VIII are pro-cofactors which are activated by thrombin during the coagulation process. Factor XIII, which is also activated by thrombin, is a transglutaminase involved in stabilizing the fibrin clot.
Hemophilic A patients have bleeding disorders because
The complex sequence of steps leading to the conversion of fibrinogen to fibrin is:
Which of the following coagulation factors belong to the group of contact activation factors?