Staphylokinase (SAK) is a promising thrombolytic agent for treating blood-clotting disorders. Recombinant SAK (rSAK) was produced after integration of the gene into Pichia pastoris genome. The recombinant Pichia carrying multiple insertions of the SAK gene yielded high-level (approximately 1 g/l) of extracellular glycosylated rSAK (approximately 18 kDa) with negligible plasminogen activation activity. Addition of tunicamycin during the induction phase resulted in expression of non-glycosylated and highly active rSAK (approximately 15 kDa) from the same clone. Two simple steps of ion-exchange chromatography produced an homogenous rSAK of >95% purity which suitable for future structural and functional studies.

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A method for improved refolding and purification of E. coli derived human Interferon -α (rhIFN α2b) from inclusion bodies as a Staphylokinase (SAK) fusion protein is described. Such a fusion protein did not require the supplementation of rare codons for expression and was found to be stable at 37 o C. The optimal conditions of refolding involved the use of a mild denaturating agent without the need for any other agents to prevent aggregation. The SAKrhIFN α2b fusion protein was successfully purified using two steps of purification and was cleaved using enterokinase into two fragments namely SAK and IFN. Both the proteins were found to be biologically active showing proper folding of both the fusion partners. The cleaved IFN showed similar retention time on RP-HPLC as the bacterial derived untagged purified IFN as well as similar molecular weight on Agilent 2100 Bioanalyzer indicating the right processing of the IFN after enterokinase cleavage. The expression levels of SAK-IFN were found to be two folds higher than that observed with untagged IFN under similar experimental conditions.

Snake venoms contain multimolecular forms of phospholipase A2 which are diverse with respect to their pharmacological properties. A neurotoxic PLA2 from Naja naja naja venom has been purified in two steps. (1) The whole venom was fractionated on CM-Sephadex C-25 column; 4.6% of the total PLA2 activity recovered was found in the NN-V fraction. (2) The NN-Vb-PLA2 fraction was purified to homogeneity by gel filtration of fraction NN-V on Sephadex G-50. It is a basic protein with a mol. wt between 10,500 and 11,000, and is more toxic than other basic PLA2s purified from Naja naja naja venom. The LD50 of NN-Vb-PLA2 is 0.27 mg/kg body wt. It induced neurotoxic symptoms in experimental mice and is devoid of myotoxic, anticoagulant and edema-inducing activities.