A pulse radiolysis investigation of the reactions of myeloperoxidase with superoxide and hydrogen peroxide

• Published in: Biochimica et biophysica acta Vol. 956; no. 1; pp. 58 - 62
• Main Authors: Kettle, Anthony J., Sangster, David F., Gebicki, Janusz M., Winterbourn, Christine C.
• Format: Journal Article
• Language: English
• Published: Amsterdam Elsevier B.V 31.08.1988; Elsevier; North-Holland
• Subjects: Analytical, structural and metabolic biochemistry; Animals; Biological and medical sciences; Enzymes and enzyme inhibitors; Ferric Compounds; Fundamental and applied biological sciences. Psychology; Horses; Hydrogen peroxide; Hydrogen Peroxide - metabolism; Kinetics; Myeloperoxidase; Neutrophils - enzymology; Oxidoreductases; Peroxidase - metabolism; Pulse radiolysis; Spectrum Analysis; Superoxide; Superoxides - metabolism; Myeloperoxidase; Superoxide; Hydrogen peroxide; Pulse radiolysis; Human; Blood cell; Enzyme; Peroxidase; Rate constant; Hydrogen Peroxides
• ISSN: 0167-4838; 0006-3002; 1879-2588; 1878-2434
• DOI: 10.1016/0167-4838(88)90297-X

Using pulse radiolysis, the rate constant for the reaction of ferric myeloperoxidase with O 2 − to give compound III was measured at pH 7.8, and values of 2.1 · 10 6 M −1 · s −1 for equine ferric myeloperoxidase and 1.1 · 10 6 M −1 · s −1 for human ferric myeloperoxidase were obtained. Under the same conditions, the rate constant for the reaction of human ferric myeloperoxidase with H 2O 2 to give compound I was 3.1 · 10 7 M −1 · s −1. Our results indicate that although the reaction of ferric myeloperoxidase with O 2 − is an order of magnitude slower than with H 2O 2, the former reaction is sufficiently rapid to influence myeloperoxidase-dependent production of hypochlorous acid by stimulated neutrophils.