Mechanism of NO Reduction by the μ-S Tetranuclear Cu Cluster of Nitrous Oxide Reductase.
Reaction thermodynamics and potential energy surfaces are calculated using density functional theory to investigate the mechanism of the reductive cleavage of the N-O bond by the μ-sulfide-bridged tetranuclear Cu site of nitrous oxide reductase. The Cu cluster provides an exogenous ligand-binding si...
| Publicado en: | Journal of the American Chemical Society Vol. 128; no. 1; pp. 278 - 291 |
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| Autores principales: | , , |
| Formato: | Artículo |
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American Chemical Society
1/11/2006
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| Acceso en línea: | Ver este registro en EBSCOhost |
| fields | @attributes: recordID: 1 pdfLink: plink: https://search.ebscohost.com/login.aspx?direct=true&db=hlh&AN=19519366&site=ehost-live header: @attributes: shortDbName: hlh uiTerm: 19519366 longDbName: Humanities International Complete uiTag: AN controlInfo: bkinfo: jinfo: jid: 00027863 ACS jtl: Journal of the American Chemical Society issn: 00027863 maglogo: N pubinfo: dt: 1/11/2006 vid: 128 iid: 1 pid: 997 pub: American Chemical Society artinfo: ui: 19519366 10.1021/ja055856o ppf: 278 ppct: 13 formats: tig: atl: Mechanism of NO Reduction by the μ-S Tetranuclear Cu Cluster of Nitrous Oxide Reductase. aug: au: Goreisky, Serge I. Ghosh, Somdatta Solomon, Edward I. affil: Department of Chemistry, Stanford University, Stanford, California 94305. su: Nitrous oxide Enzymes Density functionals Catalysis Ligands (Chemistry) Protons sug: subj: Nitrous oxide Enzymes Density functionals Catalysis Ligands (Chemistry) Protons ab: Reaction thermodynamics and potential energy surfaces are calculated using density functional theory to investigate the mechanism of the reductive cleavage of the N-O bond by the μ-sulfide-bridged tetranuclear Cu site of nitrous oxide reductase. The Cu cluster provides an exogenous ligand-binding site, and, in its fully reduced 4Cu state, the cluster turns off binding of stronger donor ligands while enabling the formation of the Cu-NO complex through enhanced Cu → NO back-donation. The two copper atoms (Cu and Cu) at the ligand-binding site of the cluster play a crucial role in the enzymatic function, as these atoms are directly involved in bridged NO binding, bending the ligand to a configuration that resembles the transition state (TS) and contributing the two electrons for NO reduction. The other atoms of the Cu cluster are required for extensive back-bonding with minimal a ligand-to-metal donation for the NO activation. The low reaction barrier (18 kcal mol) of the direct cleavage of the N-C bond in the Cu-NC complex is due to the stabilization of the TS by a strong Cu-O bond. Due to the charge transfer from the Cu cluster to the NO ligand, noncovalent interactions with the protein environment stabilize the polar TS and reduce the activation energy to an extent dependent on the strength of proton donor. After the N-C bond cleavage, the catalytic cycle consists of a sequence of alternating protonation/one- electron reduction steps which return the Cu cluster to the fully reduced (4Cu) state for future turnover. pubtype: Academic Journal doctype: Article src: R language: English refInfo: copyright: @attributes: flag: Y dt: @attributes: year: 2006 holdings: @attributes: islocal: N |
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