Catalogo Articoli (Spogli Riviste)

OPAC HELP

Titolo:
A density functional study of possible intermediates of the reaction of dioxygen molecule with nonheme iron complexes. 2. "Water-assisted" model studies
Autore:
Torrent, M; Musaev, DG; Morokuma, K; Basch, H;
Indirizzi:
Emory Univ, Cherry L Emerson Ctr Sci Computat, Atlanta, GA 30322 USA EmoryUniv Atlanta GA USA 30322 n Ctr Sci Computat, Atlanta, GA 30322 USA Emory Univ, Dept Chem, Atlanta, GA 30322 USA Emory Univ Atlanta GA USA 30322 ry Univ, Dept Chem, Atlanta, GA 30322 USA Bar Ilan Univ, Dept Chem, IL-52900 Ramat Gan, Israel Bar Ilan Univ Ramat Gan Israel IL-52900 Chem, IL-52900 Ramat Gan, Israel
Titolo Testata:
JOURNAL OF PHYSICAL CHEMISTRY B
fascicolo: 19, volume: 105, anno: 2001,
pagine: 4453 - 4463
SICI:
1520-6106(20010517)105:19<4453:ADFSOP>2.0.ZU;2-E
Fonte:
ISI
Lingua:
ENG
Soggetto:
MAGNETIC CIRCULAR-DICHROISM; METHANE MONOOXYGENASE; RIBONUCLEOTIDE REDUCTASE; CRYSTAL-STRUCTURE; OXYGEN ACTIVATION; HYDROXYLASE COMPONENT; ESCHERICHIA-COLI; ACTIVE-SITE; SUBSTRATE-BINDING; REACTION CYCLE;
Tipo documento:
Article
Natura:
Periodico
Settore Disciplinare:
Physical, Chemical & Earth Sciences
Citazioni:
51
Recensione:
Indirizzi per estratti:
Indirizzo: Torrent, M Emory Univ, Cherry L Emerson Ctr Sci Computat, Atlanta, GA 30322 USA Emory Univ Atlanta GA USA 30322 omputat, Atlanta, GA 30322 USA
Citazione:
M. Torrent et al., "A density functional study of possible intermediates of the reaction of dioxygen molecule with nonheme iron complexes. 2. "Water-assisted" model studies", J PHYS CH B, 105(19), 2001, pp. 4453-4463

Abstract

The structure and stabilities of various intermediates of the "water-assisted" O-O bond activation reaction on the MMOHred and R2(red) were studied using the B3LYP hybrid density functional method, and are compared with those for the "water-free" model studies. It was shown that the first Step of the reaction is coordination of the O-2 molecule to one of the Fe atoms of complex I_H2O ("water-assisted" model complex) leading to formation of the mixed-valence superoxo species, [Fe-II(O-2)Fe--(III)], II_H2O. Then, the second electron transfer from the other Fe atom to the O-2 moiety leads to formation of the peroxo complex [Fe-III(O-2)Fe-2-(III)], which is found to have four different isomers, III_H2O, IV_H2O, V_H2O, and VI_H2O, correspondingto the cis-mu -1,2, end-on mu -1,1, distorted trans mu -1,2, and mu-eta (2)-eta (2) coordination modes of O-2, respectively. The stability (relative to I_H2O + O-2) of these isomers increases via III_H2O (34.5 kcal/mol) < VI_H2O (36.4 kcal/mol) < V_H2O (44.7 kcal/mol) < IV_H2O (57.4 kcal/mol). On the basis of the structural analysis and calculated O-O bond distances, we have predicted that isomers III_H2O, V_H2O, and VI_H2O are intermediates on the, potential energy surface of the homolytic O-O activation process, while isomers III_H2O and IV_H2O are intermediates of the heterolytic O-O activation reaction. The homolytic O-O activation by MMOHred is predicted to occur via the following intermediates: I_H2O + O-2 + II_H2O (superoxo species)--> III_H2O (cis-mu -1,2-peroxo)--> V_H2O (distorted trans-mu -1,2-peroxo)--> VI_H2O (mu-eta (2)-eta (2) phoxo) --> VII_H2O (compound Q with water) --> VII (compound Q). Having an additional water molecule around the activesite of MMOHred (and R2(red)) facilitates the superoxo --> peroxo conversion process because of the opening of one of the "legs" of mu -1,2-bridged carboxylate leading to formation of Fe-1-HOH...OCHO-Fe-2 network.

ASDD Area Sistemi Dipartimentali e Documentali, Università di Bologna, Catalogo delle riviste ed altri periodici
Documento generato il 07/07/20 alle ore 19:22:49