PLASMINOGEN-ACTIVATOR INHIBITOR-2 (PAI-2) IS NOT INACTIVATED BY EXPOSURE TO OXIDANTS WHICH CAN BE RELEASED FROM ACTIVATED NEUTROPHILS

Purified recombinant human monocyte plasminogen activator inhibitor 2 (PAI-2) retained inhibitory activity after exposure to a number of oxidants, including hypochlorite anion (OCl-), chloramine-T (CT) and hydrogen peroxide (H2O2). Analysis of PAI-2 exposed to oxidants by gel filtration chromatography and SDS-PAGE indicated that although the protein could no longer be detected by silver staining, this was not due to fragmentation of the PAI- 2 molecule. The sensitivity of a number of serine protease inhibitors (serpins), (eg. α1 proteinase inhibitor (α1PI) and plasminogen activator inhibitor 1 (PAI-1)) to oxidative inactivation has been attributed to oxidation of reactive site methionine residues and/or tertiary structural modifications. The relevance of these phenomena and the potential for PAI-2 to be used as a therapeutic inhibitor of urokinase (uPA)-dependent proteolysis during inflammation and tumour metastasis is discussed. © 1990.