Mechanism of nitrite reduction at T2Cu centers: electronic structure calculations of catalysis by copper nitrite reductase and by synthetic model compounds.
The mechanism of nitrite reduction at the Cu(II) center of both copper nitrite reductase and a number of corresponding synthetic models has been investigated by using both QM/MM and cluster calculations employing density functional theory methods. The mechanism in both cases is found to be very similar. Initially nitrite is bound in a bidentate fashion to the Cu(II) center via the two oxygen atoms. Upon reduction of the copper center, the two possible coordination modes of the protonated nitrite, by either nitrogen or a single oxygen atom, are close in energy, with nitrogen coordination probably preferred. Further protonation of this species leads to N-O bond cleavage, and an electron transfer from the Cu(I) center to the N-O+ ligand, resulting in loss of NO and regeneration of the resting state of the enzyme having a bound water molecule.
Sundararajan
Mahesh
M
School of Chemistry, University of Manchester, Manchester, M13 9PL, United Kingdom.
Hillier
Ian H
IH
Burton
Neil A
NA
D001665:Binding Sites; D003300:Copper / Q000737:chemistry* / Q000378:metabolism; D009572:Nitrite Reductases / Q000378:metabolism*; D009573:Nitrites / Q000378:metabolism*; D010084:Oxidation-Reduction; D011487:Protein Conformation
D009573:Nitrites; D003300:Copper; D009572:Nitrite Reductases; C052695:nitrite reductase, copper-containing