[Interaction of phosphatidyl serine with fibrin monomer].

Phosphatidyl serine induces a concentration-dependent inhibition of polymerization of fibrin monomer and forms a complex with it, which is stable to gel-filtration and chloroform treatment. During plasmin proteolysis phosphatidyl serine remains tightly bound to the fragments of the fibrin monomer molecule formed. A correlation between the amount of amino acids responsible for phospholipid binding and that of phosphatidyl serine bound to the fragment of the fibrin monomer molecule was observed. The introduction of phosphatidyl serine into the blood flow causes a decrease of the thrombin-precipitated fibrinogen and fibrin monomer obtained from animal plasma. At the same time phosphatidyl serine is present in fibrinogen and in high amounts in the fibrin monomer. It is assumed that phosphatidyl serine which controls thrombinogenesis and enzymatic and non-enzymatic steps of fibrin production can thus be regarded as a natural stabilizer of the blood.