A Theoretical Study of the Cis-Dihydroxylation Mechanism in Naphthalene 1,2-dioxygenase
2004 (English)In: Journal of Biological Inorganic Chemistry, ISSN 0949-8257, E-ISSN 1432-1327, Vol. 9, no 4, 439-452 p.Article in journal (Refereed) Published
The catalytic mechanism of naphthalene 1,2-dioxygenase has been investigated by means of hybrid density functional theory. This Rieske-type enzyme, which contains an active site hosting a mononuclear non-heme iron(II) complex, uses dioxygen and two electrons provided by NADH to carry out the cis-dihydroxylation of naphthalene. Since a (hydro)peroxo-iron(III) moiety has been proposed to be involved in the catalytic cycle, it was probed whether and how this species is capable of cis-dihydroxylation of the aromatic substrate. Different oxidation and protonation states of the Fe–O2 complex were studied on the basis of the crystal structure of the enzyme with oxygen bound side-on to iron. It was found that feasible reaction pathways require a protonated peroxo ligand, FeIII–OOH; the deprotonated species, the peroxo-iron(III) complex, was found to be inert toward naphthalene. Among the different chemical patterns which have been explored, the most accessible one involves an epoxide intermediate, which may subsequently evolve toward an arene cation, and finally to the cis-diol. The possibility that an iron(V)-oxo species is formed prior to substrate hydroxylation was also examined, but found to implicate a rather high energy barrier. In contrast, a reasonably low barrier might lead to a high-valent iron-oxo species [i.e. iron(IV)-oxo] if a second external electron is supplied to the mononuclear iron center before dioxygenation.
Place, publisher, year, edition, pages
2004. Vol. 9, no 4, 439-452 p.
Density functional calculations, Enzyme catalysis, Non-heme iron enzymes, O–O bond activation
IdentifiersURN: urn:nbn:se:su:diva-22674DOI: 10.1007/s00775-004-0537-0OAI: oai:DiVA.org:su-22674DiVA: diva2:189250
Part of urn:nbn:se:su:diva-1032004-04-152004-04-152010-07-27Bibliographically approved