title: Nitric oxide activation by caa3 oxidoreductase from Thermus thermophilus.
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.
authors.affiliation: Graduate School of Life Science, University of Hyogo, Hyogo 678-1297, Japan.
authors.forename: Takehiro
authors.initials: T
authors.lastname: Ohta
authors.forename: Tewfik
authors.initials: T
authors.lastname: Soulimane
authors.forename: Teizo
authors.initials: T
authors.lastname: Kitagawa
authors.forename: Constantinos
authors.initials: C
authors.lastname: Varotsis
mesh_terms: D003574:Cytochrome c Group / Q000378:metabolism*; D045264:Cytochromes a / Q000378:metabolism*; D045266:Cytochromes a3 / Q000378:metabolism*; D006418:Heme / Q000378:metabolism; D008024:Ligands; D009569:Nitric Oxide / Q000378:metabolism*; D016963:Thermus thermophilus / Q000201:enzymology*
chemical_list: D003574:Cytochrome c Group; D045266:Cytochromes a3; D008024:Ligands; C435384:cytochrome caa(3); D009569:Nitric Oxide; D006418:Heme; D045264:Cytochromes a