Direct acting anti-thrombotic serine protease from brown seaweed Costaria costata

► We report a new enzyme from Costaria costata, which was able to dissolve fibrin clot and human fibrinogen effectively. ► The ability of enzyme to induce changes in the secondary structure of fibrin and fibrinogen molecules was also observed. ► The enzyme exhibited prophylactic antithrombotic effects. ► The enzyme showed anticoagulant and antiplatelet properties.