Streptokinase clot selectivity

Anistreplase (anisoylated plasminogen streptokinase activator complex APSAC) consists of a complex of purified human plasminogen and bacterial streptokinase that has been acylated to protect the enzyme s active site. When administered, the acyl group spontaneously hydrolyzes, freeing the activated streptokinase-proactivator complex. This product (recently discontinued in the USA) allows for rapid intravenous injection, greater clot selectivity (ie, more activity on plasminogen associated with clots than on free plasminogen in the blood), and more thrombolytic activity. 

Anisoylatedplasminogen streptokinase activator complex (APSAC)(Table 11-4) is an anisoyl (p-methoxybenzoyl) derivative of the active (lysine) site of the plasminogen component of this complex. Acylation inactivates the enzyme but does not decrease the affinity of the complex for fibrin. The resultant slow deacylation (tU2 = 40 min) should achieve relative selectivity for the fibrin in the clot over circulating plasma fibrinogen. Hydrolysis of anisoyl amide following binding onto the thrombus (i.e., activation) leads to fibrinolysis. APSAC has been reported to produce a 60-80% reperfusion rate following IV administration. 

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