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
Aa chain of fibrinogen and then the Bb-chain, but not the
c-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.