RENATURATION, PURIFICATION, AND CHARACTERIZATION OF HUMAN PLASMINOGEN-ACTIVATOR INHIBITOR TYPE-2 (PAI-2) ACCUMULATED AT HIGH-LEVEL IN ESCHERICHIA-COLI

Plasminogen activator inhibitor 2 (PAI-2) is an important regulator of plasminogen activation, which inhibits both tissue-type plasminogen a ctivator (tPA) and urokinase-type plasminogen activator (uPA), In this study we have developed a high-level expression system by inserting a modified PAI-2 gene downstream of the T7 promoter, The expression lev el of recombinant PAI-2 amounted to 55-60% of total microbial protein, By efficient renaturation and one-step purification, the recombinant protein was purified to homogeneity, The specific activity and yield o f recombinant PAI-2 reached 33,000 IU/mg and 10 mg per gram wet weight of Escherichia coli cells, respectively, The second-order rate consta nt for uPA was 2.6-2.8 x 10(5) M-1. s(-1).