A pulse radiolysis investigation of the reactions of myeloperoxidase with superoxide and hydrogen peroxide.
Using pulse radiolysis, the rate constant for the reaction of ferric myeloperoxidase with O2- 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 H2O2 to give compound I was 3.1.10(7) M-1.s-1. Our results indicate that although the reaction of ferric myeloperoxidase with O2- is an order of magnitude slower than with H2O2, the former reaction is sufficiently rapid to influence myeloperoxidase-dependent production of hypochlorous acid by stimulated neutrophils.
Kettle
A J
AJ
Department of Pathology, Christchurch School of Medicine, Christchurch Hospital, New Zealand.
Sangster
D F
DF
Gebicki
J M
JM
Winterbourn
C C
CC
D000818:Animals; D005290:Ferric Compounds; D006736:Horses; D006861:Hydrogen Peroxide / Q000378:metabolism*; D007700:Kinetics; D009504:Neutrophils / Q000201:enzymology; D009195:Peroxidase / Q000378:metabolism*; D013057:Spectrum Analysis; D013481:Superoxides / Q000378:metabolism*
D005290:Ferric Compounds; D013481:Superoxides; D006861:Hydrogen Peroxide; D009195:Peroxidase