EN
2 The human fibrinolytic system comprises an inactive proenzyme ? plasminogen which can be converted to the active form ? plasmin which, in turn, degrades fibrin clots into soluble fibrin degradation products. Tissue plasminogen activator (t-PA) has been identified as a main physiological factor responsible for plasminogen - plasmin conversion. The high fibrin specificity of t-PA, which allows efficient activation on the surface of fibrin clots, has stimulated great interest in its preparation to be used for thrombolytic therapy. Several approaches have been followed to further improve the thrombolytic properties of recombinant t-PA by protein engineering to enhance its plasminogen - activating potency as well as fibrin specificity, and to reduce its plasma clearance. One of the approaches involves the conjugation of its deletion variant, so called K2L-tPA, to various biomolecules. K2L-tPA is a 351-aminoacid C-terminal fragment of human t-PA. The protein is composed of two major domains: Kringle-2 (K2), responsible for fibrin binding, and so-called Light Chain domain (L), containing active centre of the enzyme. In this paper, we describe our efforts on expression of synthetic gene coding for K2L-tPA, and on renaturation and purification of recombinant protein