Two des-kringle derivatives of human plasminogen, microplasminogen and miniplasminogen, have been expressed at high levels as inclusion bodies in Escherichia coli using a T7 expression system. In each case, the isolated inclusion bodies were refolded and purified. A final yield of similar to 10% of total refolded protein was observed in each case. Both refolded molecules were successfully activated to their functional forms, microplasmin and miniplasmin, by the plasminogen activator urokinase. The kinetic properties of the refolded microplasmin and miniplasmin were comparable to full length, native plasmin. (c) 2006 Elsevier Inc. All rights reserved.