Structure and properties of the catalytic site of nitric oxide reductase at ambient temperature

Nitric oxide reductase (Nor) is the third of the four enzymes of bacterial denitrification responsible for the catalytic formation of laughing gas (N2O). Here we report the detection of the hyponitrite (HO-N = N-O-) species (v(N-N) = 1332 cm(-1)) in the heme b(3) Fe-Fe-B dinuclear center of Nor from Paracoccus denitrificans. We have also applied density functional theory (DFT) to characterize the bimetallic-bridging hyponitrite species in the reduction of NO to N2O by Nor and compare the present results with those recently reported for the N-N bond formation in the ba(3) and caa(3) oxidoreductases from Therms thermophilus. (C) 2015 Elsevier B.V. All rights reserved.