HIGH-LEVEL EXPRESSION OF ACTIVE HUMAN PLASMINOGEN-ACTIVATOR INHIBITORTYPE-1 (PAI-1) IN ESCHERICHIA-COLI

Plasminogen activator inhibitor 1 (PAI-1) is an important regulator of plasminogen activation which inhibits both tissue-type plasminogen ac tivator (tPA) and urokinase-type plasminogen activator (uPA). The DNA sequence encoding mature PAI-1 protein was inserted into an inducible expression vector. This gene was highly expressed to produce a soluble active protein iu E. coli cells. The amount of the recombinant protei n was up to 20% of total cellular protein. By efficient purification w ith a yield of about 15-20%, the recombinant protein could be purified to homogeneity with its specific activity up to 6.1x10(4) (uPA) IU/mg . Its inhibitory activity declined during incubation at 37 degrees C w ith a half life of about 2 hr.