Uber den Reak-tionsmechanismus der Hemmung der Blutgerinnung durch einige seltene Erden und durch Heparin
Dyckerhoff, H.; Grunewald, D.
Biochemische Zeitschrift 315(2): 124-138
ISSN/ISBN: 0366-0753 Accession: 026034495
In the 1st phase of blood clotting, the coagulation enzyme, thrombin, is formed from prothrombin under the influence of thrombokinase and Ca ion. In the 2d phase, thrombin changes soluble fibrinogen into fibrin, profibrin being an intermediate product. In the expts. reported, cooked lung extract is used as a source of thrombokinase. The methods for the detn. of thrombokinase activity, thrombin content and prothrombin activity have been reported previously (Biochem. Zeitschr., 313: 107, 116, 1943). When the various substances used are purified, heparin can not inhibit the 1st phase of blood clotting. In plasma, heparin proves to be a powerful anti-thrombin. Salts of the rare earths, such as neodymium, samarium and cerium acetate, and praseodymium and erbium Cl, inhibit the 1st phase of blood clotting and are true antiprothrombins. The rare earths have no influence on the 2d phase. Heparin and the rare earths are antagonists of thrombokinase, which cannot overcome entirely the inhibiting effect of these substances. These conclusions are valid only for the adsorptive but not for the proteo-. lytic activity of prothrombin.