Correlation of kinetic parameters of nitroreductase enzymes with redox properties of nitroaromatic compounds

The well-established mechanism of regeneration of the parent nitro compound by the reaction of the nitro anion radical with oxygen in aerobic systems is the basis of the correlation of kinetic parameters of purified flavoenzymes with electron affinities of some selected nitroaryl and nitroheterocyclic compounds. We have found that there is a linear relationship between log Vmax/Km and the one-electron reduction potentials of these compounds and that the measured values of redox dependence for these compounds is similar to that determined by other methods. Our results support the proposal of a rate-determining single electron-transfer as the initial step in the reduction of nitro compounds by purified flavoenzymes and are discussed in terms of the Marcus electron transfer theory.