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 activator (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 level 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 of recombinant PAI-2 reached 33,000 IU/mg and 10 mg per gram wet weight of Escherichia coli cells, respectively. The second-order rate constant for uPA was 2.6-2.8 x 10(6) M(-1) x s(-1).