Many heme proteins like myoglobin catalyze the oxygenation of nitric oxide, the so called NO Dioxygenase reactivity. This reactivity can be accessed from the reaction of oxyMb with NO, or of NO-Mb with O2, yeilding metMb and nitrate as products. Questions remain about the mechanism of the reaction and the nature of a short-lived intermediate observed on the millisecond timescale with a characteristic absorbance at 636 nm. We observed two spectrally similar intermediates in the reaction of O2 with HNO-Mb under different conditions. Under nitrogen headgas, the formation and decomposition of the intermediate species are both pH and O2 dependent. Interestingly, in reactions carried out under a CO atmosphere the intermediate absorbance is shifted and the major product is CO-Mb. Mechanistic interpretations will be discussed.

Intermediates in nitric oxide dioxygenase reactivity

248th National Meeting (2014)

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