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Updated: Apr 15, 2026

Chemiluminescence-based Assays for Detection of Nitric Oxide and its Derivatives from Autoxidation and Nitrosated Compounds
Published on: February 16, 2022
Nitric oxide activation by caa3 oxidoreductase from Thermus thermophilus
Takehiro Ohta1, Tewfik Soulimane, Teizo Kitagawa
1Graduate School of Life Science, University of Hyogo, Hyogo 678-1297, Japan.
Abstract:
Visible and UV-resonance Raman spectroscopy was employed to investigate the reaction of NO with cytochrome caa3 from Thermus thermophilus. We show the formation of the hyponitrite (HO-N=N-O)(-) bound to the heme a3 species (νN=N = 1330 cm(-1)) forming a high spin complex in the oxidized heme a3 Fe/CuB binuclear center of caa3-oxidoreductase. In the absence of heme a3 Fe(2+)-NO formation, the electron required for the formation of the N=N bond originates from the autoreduction of CuB by NO, producing nitrite. With the identification of the hyponitrite intermediate the hypothesis of a common phylogeny of aerobic respiration and bacterial denitrification is fully supported and the mechanism for the 2e(-)/2H(+) reduction of NO to N2O can be described with more certainty.
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