A comparison of the esterase (TAMe) and clotting activities of human and bovine thrombin preparations.

A comparison has been made between the clotting activity (C) and TAMe esterase activity (E) during prothrombin activation and subsequent purification of human thrombin. A limited number of studies were made using bovine thrombin for comparison purposes. Under certain circumstances, the ratio of C to E for human thrombin is not constant, particularly upon gel-filtration at low ionic strength and during prolonged contact with 25% sodium citrate. Under other circumstances, however, these enzymic parameters are stable and human thrombin appears to have a ratio of C to E of approximately 6 while bovine thrombin has a ratio of 3. This finding may confirm the observations of others concerning the higher specific activity of human thrombin than the bovine enzyme against bovine fibrinogen. Only a single component having C and E activity has been isolated from human prothrombin preparations activated to thrombin by sodium citrate or biologically and purified by either gel filtration or ion exchange chromatography. Kinetic studies on human thrombin preparations indicate that in all other respects they are similar in enzymic properties to those reported for the purified bovine enzyme.