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Spectroscopic and computational studies of nitrite reductase: proton induced electron transfer and backbonding contributions to reactivity.

ABSTRACT: A combination of spectroscopy and DFT calculations has been used to define the geometric and electronic structure of the nitrite bound type 2 (T2) copper site at high and low pH in nitrite reductase from Rhodobacter sphaeroides. At high pH there is no electron transfer from reduced type 1 (T1) to the nitrite bound T2 copper, while protonation triggers T1 --> T2 electron transfer and generation of NO. The DFT calculated reaction coordinate for the N-O bond cleavage in nitrite reduction by the reduced T2 copper suggests that the process is best described as proton transfer triggering electron transfer. Bidentate nitrite binding to copper is calculated to play a major role in activating the reductive cleavage of the nitrite bond through backbonding combined with stabilization of the (-)OH product by coordination to the Cu(2+).

SUBMITTER: Ghosh S

PROVIDER: S-EPMC2629382 | biostudies-literature | 2009 Jan

REPOSITORIES: biostudies-literature

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Spectroscopic and computational studies of nitrite reductase: proton induced electron transfer and backbonding contributions to reactivity.

Ghosh Somdatta S Dey Abhishek A Sun Yan Y Scholes Charles P CP Solomon Edward I EI

Journal of the American Chemical Society 20090101 1

A combination of spectroscopy and DFT calculations has been used to define the geometric and electronic structure of the nitrite bound type 2 (T2) copper site at high and low pH in nitrite reductase from Rhodobacter sphaeroides. At high pH there is no electron transfer from reduced type 1 (T1) to the nitrite bound T2 copper, while protonation triggers T1 --> T2 electron transfer and generation of NO. The DFT calculated reaction coordinate for the N-O bond cleavage in nitrite reduction by the red ...[more]

PMID: 19053185

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