Streptokinase E.P.

Streptokinase is an enzyme produced by β-hemolytic group C bacterial cells that can solve blood clots by converting plasminogen to plasmin. It is a widely used thrombolytic agent i.e. it dissolves vascular thrombi. It induces its thrombolytic effect by binding specifically and tightly to plasminogen. This induces a conformational change in the plasminogen molecule which renders it proteolytically active.
The streptokinase plasminogen complex catalyses the proteolytic conversion of plasminogen to active plasmin. This aids in the dissolution of the clot.

Structure

Streptokinase is a highly purified bacterial protein extracted from the culture filtrate of certain strains of Streptococcus Group C. It is a single chain glycoprotein with a molecular weight of 45,000 – 50,000 Da and very low carbohydrate content (< 10 %). It has one major isoelectric point at pH 4.95. A primary structure determination reveals isoleucine at the amino terminal, lysine at the carboxy terminal and the absence of any intra-chain disulphide bridges.