Does diphenylene iodonium chloride have any effect on the O2‐generating step of plant peroxidases?

Abstract
The O2 ‐generating step of plant peroxidases during their catalytic cycle is represented by the decay of compound III (CoIII) into ferriperoxidase, which most likely involves the dissociation of a ferric‐O2 complex to yield the ferric form of the enzyme and O2 . Diphenylene iodonium chloride (DPI), at 50–100 μM, does not significantly enhance the stability of CoIII of peroxidase, as judged by the values of k decay, and therefore, DPI appears to have no effect on the O2 ‐generating step of plant peroxidases. From these results, it is concluded that caution should be exercized when considering peroxidase as a possible enzyme target of O2 ‐mediated plant physiological processes sensitive to DPI inhibition.