PEROXIDE-INDUCED DAMAGE TO PLASMINOGEN MOLECULES
Plasminogen is a zymogenic form of plasmin, an enzyme that plays a fundamental role in the dissolution of fibrin clots as well as participating in many other physiological processes. For the first time, by the method of gas chromatography-mass spectrometry post-translational modifications in the primary structure of plasminogen treated with physiologically relevant amounts of hydrogen peroxide were identified. It was found that methionine and tryptophan residues localized in different structural regions of plasminogen served as targets the oxidant. Plasminogen oxidation caused a dose-dependent effect in decreasing the fibrinogenolytic activity of plasmin evidenced by the formation of fibrinogen degradation products. The possible antioxidant role of methionines in the oxidative modification of plasminogen is discussed.