Copper, heme-copper or heme containing metalloprotein active sites mediate important reactions involving nitrogen oxides. While nitric oxide (NO) is a critically important signaling agent, or an intermediate in various biochemical pathways/cycles, its cellular concentrations must be tightly controlled. Heme/non-heme diiron bacterial NO Reductases can reductively couple NO to give nitrous oxide (N2O), via putative hyponitrite intermediates; this reaction may also be effected by heme-copper oxidases. On the other hand NO may be oxidized to nitrite by heme-copper oxidases, or to nitrate by oxy-globins, with the proposed intermediacy of peroxynitrite (–O-O-N=O). Peroxynitrite may form in aqueous solution by reaction of superoxide anion with NO. We have found that we can reductively couple NO to give N2O via hyponitrite intermediates, using copper ion, either starting with mononuclear or binuclear Cu complexes. Utilizing similar systems, we can also carry out Cun/O2/NO reactions to give peroxynitrite compounds. Results from some of these chemical systems will be presented, including with findings from mechanistic interrogations.

Bioinorganic aspects of nitrogen monoxide (NO) oxidation or reduction chemistry mediated at copper or heme centers

255th National Meeting (2018)

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