Prothrombin is the most important clotting factor in coagulation of blood. The coagulation of blood takes place in following ways-
Prothrombin is chemically in active which is converted or made active moiety as thrombin
The enzyme or factor associated with conversion is prothrombinase or factor x
Now thrombin gets converted to fibrinogen which when comes in contact with platelets present in blood results in clot formation.