Nitrous oxide (N2O) is a potent greenhouse gas produced by certain microbial heme-containing enzymes. Heme complexes of hyponitrite (-O-N=N-O-) and its protonated forms, HO-N=N-O- (pKa 11.5) and HO-N=N-OH (pKa 7.2) are proposed precursors to N2O formed by the monoheme fungal cytochrome P450 nitric oxide (NO) reductase, as well as the binuclear heme/non heme active site of bacterial NO reductase. A heme hyponitrite complex is also a possible intermediate in the oxidation of hydroxylamine (NH2OH) to N2O, catalyzed by cytochrome P460. As a first step towards defining the spectroscopic signatures of monoheme hyponitrite complexes, we used UV-visible absorption to study the reactivity of hyponitrite with a range of bacterial heme proteins.

Hyponitrite reactivity with heme proteins

2019 Spring National Meeting

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