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Theoretical study of the catalytic mechanism of catechol oxidase.

Authors :
Güell, Mireia
Siegbahn, Per E. M.
Source :
Journal of Biological Inorganic Chemistry (JBIC). Dec2007, Vol. 12 Issue 8, p1251-1264. 14p. 18 Diagrams, 4 Charts, 1 Graph.
Publication Year :
2007

Abstract

The mechanism for the oxidation of catechol by catechol oxidase has been studied using B3LYP hybrid density functional theory. On the basis of the X-ray structure of the enzyme, the molecular system investigated includes the first-shell protein ligands of the two metal centers as well as the second-shell ligand Cys92. The cycle starts out with the oxidized, open-shell singlet complex with oxidation states Cu2(II,II) with a μ-η2:η2 bridging peroxide, as suggested experimentally, which is obtained from the oxidation of Cu2(I,I) by dioxygen. The substrate of each half-reaction is a catechol molecule approaching the dicopper complex: the first half-reaction involves Cu(I) oxidation by peroxide and the second one Cu(II) reduction. The quantitative potential energy profile of the reaction is discussed in connection with experimental data. Since no protons leave or enter the active site during the catalytic cycle, no external base is required. Unlike the previous density functional theory study, the dicopper complex has a charge of +2. [ABSTRACT FROM AUTHOR]

Details

Language :
English
ISSN :
09498257
Volume :
12
Issue :
8
Database :
Academic Search Index
Journal :
Journal of Biological Inorganic Chemistry (JBIC)
Publication Type :
Academic Journal
Accession number :
27053527
Full Text :
https://doi.org/10.1007/s00775-007-0293-z