Validation of the Chromogenic Bioassay for the Potency Assessment of Streptokinase in Biopharmaceutical Formulations

Streptokinase (STK) is clinically used world-wide as a thrombolytic agent to treat patients with acute myocardial infarction, deep vein thrombosis, arterial thrombosis and embolism [1-3]. The structure of STK consists of a 414 amino acids polypeptide chain with a molecular mass of 47 kDa. The protein exhibits its maximum activity at a pH of approximately 7.5 and its pI is 4.7. Most of the native Streptokinases (STKs) are obtained from pathogenic β-hemolytic streptococci A, C and G, being the group C preferred as they lack erythrogenic toxins. Recombinant STKs have been produced with reduced immunogenicity, and the gene from Streptococcus equisimilis H46A was first cloned and expressed in E. coli releasing substantial amounts of STK into the culture medium [4-6]. Besides, the STK isolated hitherto may contain the enzymes streptodornase and streptolysin O, which are active even in small quantities [7].