| Abstract: | Prethrombin 2, the direct precursor of thrombin, was obtained by restricted proteolysis of prethrombin 1 by trypsin or by active factor X. In the absence of enzymes, prethrombin 1 is not converted into prethrombin 2. Factor V was shown not to affect the rate of thrombin generation from prethrombin 2. It was shown that prethrombin 2 has no intrinsic coagulating or esterase activity. After intravenous injection of preparations of prethrombin 2, the plasma recalcification time was lengthened and total fibrinolytic activity and nonenzymic fibrinolysis were increased. A considerable increase also was found in the activity of the fibrinogen-heparin complex. These results are evidence of excitation of the anticlotting system by intravenous injection of small doses of prethrombin 2.Laboratory of Physiology and Biochemistry of Blood Clotting, M. V. Lomonosov Moscow University. (Presented by Academician of the Academy of Medical Sciences of the USSR S. E. Severin.) Translated from Byulleten' Éksperimental'noi Biologii i Meditsiny, Vol. 89, No. 3, pp. 270–272, March, 1980. |
