[Anticoagulant and fibrinolytic effects of proline-containing peptides].

Anticoagulant, fibrinolytic, and fibrin-depolymerization effects were revealed during in vitro study of five proline-containing peptides (Gly-Pro, Trp-Pro, Pro-Gly, Gly-Pro-Gly-Gly, and Pro-Gly-Pro) in the concentration range 10(-9) to 10(-1) mg/ml. Intravenous injection of Trp-Pro and Pro-Gly into white rats at 250 micrograms/kg body weight significantly increased recalcification time and activated partial thromboplastin time of serum coagulation, increased fibrinolytic activity, decreased the level of serum factor XIII/(/)a and fibrinogen, and reduced thrombocyte aggregation. We propose inhibition of thromboplastin and thrombin formation in the serum by the studied proline-containing peptides both in vitro and in vivo.