Mechanism of action of heparin through thrombin on blood coagulation.

It has been suggested that heparin can affect blood coagulation through thrombin, i.e. the binding of heparin to thrombin induces a conformational change in the enzyme, facilitating a complex formation between thrombin and antithrombin (Machovich, T., Blaskó, Gy. and Pálos, L. (1975) Biochim. Biophys. Acta 379, 193-200). This hypothesis seems to have been proved. Modification of arginine residues in thrombin did not result in decreased thrombin activity and decreased sensitivity to antithrombin, whereas the heparin sensitivity of the enzyme and the thrombin-antithrombin reaction were diminished.