Spectral and kinetic evidence for reaction of superoxide with compound I of myeloperoxidase.

Superoxide and myeloperoxidase (MPO) are essential for the oxidative killing of bacteria by neutrophils. Previously, we developed a kinetic model to demonstrate that within the confines of neutrophil phagosomes, superoxide should react exclusively with MPO and be converted to hypochlorous acid. The model consists of all known reactions and rate constants for reactions of superoxide, hydrogen peroxide, and chloride ions with MPO, except for the reaction of superoxide with compound I, which could only be estimated.