Cupincin: A Novel Cupin Domain Containing Protease from Rice (Oryza sativa L.) Bran Comprising of Procoagulant and Fibrinogenolytic Activity.

The current study was carried out to evaluate the pharmacological properties of cupincin- A novel cupin domain containing metalloprotease with limited proteolysis from rice bran on blood coagulation and hydrolysis of human fibrinogen. Cupincin preferentially hydrolyzed the Aα chain of fibrinogen and then the Bβ-chain, but not the γ-chain. Cupincin reduced the re-calcification time of citrated human plasma dose dependently. Analysis of citrated whole blood in the presence of cupincin by rotem showed a decrease in coagulation time and clot formation time. Sonoclot analysis indicated that cupincin cleaved fibrinogen of whole citrated blood. SDS-PAGE and sonoclot analysis (LI-30) indicated that cupincin lacked plasmin-like activity. Global hemostasis tests like rotem and sonoclot analysis determined cupincin as a procoagulant enzyme. Cupincin did not show any effect on prothrombin time and activated partial thromboplastin time tests suggesting its action on the common pathway of coagulation. The involvement of proteases from rice (Oryza sativa L.) in haemostasis has never been exploited before. This study could provide the basis for the development of new procoagulant agents from a nontoxic source like rice.