[Isolation and purification of placental coagulation inhibitor].

The placenta contains such thrombotic factors as tissue thromboplastin, placental factor XIII, and placental urokinase inhibitor. On the other hand, there are some antithrombotic factors, for example, placental plasminogen activator and platelet aggregation inhibitor. This paper deals with another antithrombotic factor isolated from the human placenta. The results obtained are as follows: The placental coagulation inhibitor (PCI) was isolated from the human placental extract, by delipidation and chromatographic procedures with Con-A Sepharose, DEAE-Sephacel and gel filtration with Sephacryl S-300 and Sephadex G-100. The PCI was a protein, having a molecular weight of approximately 45,000 daltons. Immunological examination revealed that the PCI was different from such well-known anticoagulants as AT-III, alpha 1-AT, alpha 2-M, C1-INA, and the PCI had no heparin like characteristics. The PCI had neither fibrinolytic nor antifibrinolytic activity. Platelet aggregation was not inhibited by the PCI. The PCI had anticoagulant activity which prolongs both intrinsic and extrinsic coagulation systems.