The action of some water-soluble poly-α-amino-acids on blood clotting

Abstract

Synthetic basic poly-alpha-amino acids (poly-L-lysine, poly-DL-ornithine) retard blood clotting markedly in a concn. of about 100 [mu]g./ml. blood. The neutral water-soluble poly-alpha-amino-acid (poly-DL-alanine) and the acidic poly-alpha-amino-acids (poly-aspartic acid and poly-D-glutamic acid) show no anticoagulant activity in the concn. range studied. The basic poly-amino acids inhibit thrombin formation in blood and plasma. Incubation with poly-L-lysine markedly diminishes the ability of thromboplastin to convert prothrombin into thrombin. The sensitivity of fibrinogen to thrombin and the antithrombic activity of serum are not influenced by the basic poly-amino acids. The clot-retarding action of heparin is neutralized by the basic poly-amino acids. The neutral and acidic poly-amino acids do not manifest antiheparin activity. The anticoagulant activity of the basic poly-amino acids and of protamine may be neutralized by heparin as well as by the acidic poly-amino acids. The similarity of the mode of action of synthetic water-soluble basic poly-amino acids and of natural protamine on blood coagulation and heparin is pointed out.