Can Reduction of NO to N2O in Cytochrome c Dependent Nitric Oxide Reductase Proceed through a Trans-Mechanism?

Biochemistry ◽  
2016 ◽  
Vol 56 (1) ◽  
pp. 120-131 ◽  
Author(s):  
Margareta R. A. Blomberg
Keyword(s):  
Nitric Oxide ◽  
Cytochrome C ◽  
Nitric Oxide Reductase ◽  
Reduction Of No

Proton transfer in bacterial nitric oxide reductase

2006 ◽  
Vol 34 (1) ◽  
pp. 188-190 ◽  
Author(s):  
U. Flock ◽  
J. Reimann ◽  
P. Ädelroth
Keyword(s):  
Nitric Oxide ◽  
Proton Transfer ◽  
Structural Model ◽  
No Reduction ◽  
Paracoccus Denitrificans ◽  
Proton Donor ◽  
Nitric Oxide Reductase ◽  
Reduction Of No ◽  
Proton Coupled Electron Transfer ◽  
Electron Reduction

The NOR (nitric oxide reductase) from Paracoccus denitrificans catalyses the two-electron reduction of NO to N2O (2NO+2H++2e−→N2O+H2O). The NOR is a divergent member of the superfamily of haem-copper oxidases, oxygen-reducing enzymes which couple the reduction of oxygen with translocation of protons across the membrane. In contrast, reduction of NO catalysed by NOR is non-electrogenic which, since electrons are supplied from the periplasmic side of the membrane, implies that the protons needed for NO reduction are also taken from the periplasm. Thus NOR must contain a proton-transfer pathway leading from the periplasmic side of the membrane into the catalytic site. The proton pathway has not been identified, and the mechanism and timing of proton transfer during NO reduction is unknown. To address these questions, we have studied the reaction between NOR and the chemically less reactive oxidant O2 [Flock, Watmough and Ädelroth (2005) Biochemistry 44, 10711–10719]. When fully reduced NOR reacts with O2, proton-coupled electron transfer occurs in a reaction that is rate-limited by internal proton transfer from a group with a pKa of 6.6. This group is presumably an amino acid residue close to the active site that acts as a proton donor also during NO reduction. The results are discussed in the framework of a structural model that identifies possible candidates for the proton donor as well as for the proton-transfer pathway.

scholarly journals Investigation of cytochrome c dependent nitric oxide reductase (cNOR) from Paracoccus denitrificans

2016 ◽  
Vol 1857 ◽  
pp. e91
Author(s):  
Sinan Sabuncu ◽  
Josy Ter Beek ◽  
Madeleine Strickland ◽  
Pia Ädelroth ◽  
Frederic Melin ◽  
...  
Keyword(s):  
Nitric Oxide ◽  
Cytochrome C ◽  
Paracoccus Denitrificans ◽  
Nitric Oxide Reductase

Partial and complete denitrification in Thermus thermophilus: lessons from genome drafts

2011 ◽  
Vol 39 (1) ◽  
pp. 249-253 ◽  
Author(s):  
Carlos Bricio ◽  
Laura Alvarez ◽  
Manuel J. Gómez ◽  
José Berenguer
Keyword(s):  
Nitric Oxide ◽  
Cytochrome C ◽  
Nitrate Reductase ◽  
Nitrogen Balance ◽  
Nitrite Reductase ◽  
Thermus Thermophilus ◽  
Variable Region ◽  
Nitric Oxide Reductase ◽  
Genes Encoding ◽  
Cytochrome Cd1

We have obtained draft genomic sequences of PD (partial denitrificant) and CD (complete denitrificant) strains of Thermus thermophilus. Their genomes are similar in size to that of the aerobic strains sequenced to date and probably contain a similar megaplasmid. In the CD strain, the genes encoding a putative cytochrome cd1 Nir (nitrite reductase) and ancillary proteins were clustered with a cytochrome c-dependent Nor (nitric oxide reductase), and with genes that are probably implicated in their regulation. The Nar (nitrate reductase) and associated genes were also clustered and located 7 kb downstream of the genes coding for the Nir. The whole nar–nir–nor denitrification supercluster was identified as part of a variable region of a megaplasmid. No homologues of NosZ were found despite nitrogen balance supports the idea that such activity actually exists.

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