Resonance Raman of the nitrite reductase action of heme-copper oxidoreductases.

Several themes have emerged in the studies of biological control of nitrite and nitric-oxide chemistry.[1-2] Apparently, evolution has clearly selected means by which to take advantage of the unique NO and NO chemistry, and a number of enzymes have evolved that are able to activate NO /NO kinetically, and control their redox chemistry. In bacterial respiration the reduction of NO /NO to N O by terminal oxidoreductases supports the hypothesis of a common evolutionary origin of bacterial denitrification and aerobic respiration. Comparison of the enzymes responsible for the activation of NO in denitrification and bacterial respiration may provide the means to identify conserved structural features, which can be assumed to be involved in basic functions common to both classes of enzymes. The most commonly encountered metals in the biological reduction of NO to NO and subsequently to N O are iron and copper in mononuclear, binuclear, and dinuclear centers. In P450Nor the electrons needed for the reduction of NO are directly transferred from NADH. This way, a single molecule of NO binds at the heme Fe, and addition of two electrons to heme Fe -NO yields the two electron reduced species Fe -N=O . A second NO moleculeattacks the N atom of the ferrous-NO species to transiently yield hyponitrite (HONNO ), and thus the N-N bond formation. Cleavage of the N-O bond produces the ferric enzyme, N O and H O. Resonance Raman studies of the NO -ligand binding properties of heme-copper oxidases will be presented. References. Discrete Ligand Binding and Electron Transfer Properties of ba -Cytochrome c Oxidase from Thermus thermophilus: Evolutionary Adaption to Low Oxygen and …C Koutsoupakis, T Soulimane, C. Varotsis Accounts of chemical research 52 (5), 1380-139, 2019. The structure of a ferrous heme-nitro species in the binuclear heme a3/CuBcenter of ba3-cytochrome c oxidase as determined by resonance Raman spectroscopy A. Loullis, MR Noor, T Soulimane, E Pinakoulaki Chemical Communications 51 (2), 286-289, 2015.