Tungsten-dependent formaldehyde ferredoxin oxidoreductase: Reaction mechanism from quantum chemical calculations
2011 (English)In: Journal of Inorganic Biochemistry, ISSN 0162-0134, E-ISSN 1873-3344, Vol. 105, no 7, 927-936 p.Article in journal (Refereed) Published
Formaldehyde ferredoxin oxidoreductase from Pyrococcus furiosus is a tungsten-dependent enzyme thatcatalyzes the oxidation of formaldehyde to formic acid. In the present study, quantum chemical calculationsare used to elucidate the reaction mechanism of this enzyme. Several possible mechanistic scenarios areinvestigated with a large model of the active site designed on the basis of the X-ray crystal structure of thenative enzyme. Based on the calculations, we propose a new mechanism in which the formaldehyde substratebinds directly to the tungsten ion.WVI=O then performs a nucleophilic attack on the formaldehyde carbon toform a tetrahedral intermediate. In the second step, which is calculated to be rate limiting, a proton istransferred to the second-shell Glu308 residue, coupled with a two-electron reduction of the tungsten ion.The calculated barriers for the mechanism are energetically very feasible and in relatively good agreementwith experimental rate constants. Three other second-shell mechanisms, including one previously proposedbased on experimental findings, are considered but ruled out because of their high barriers.
Place, publisher, year, edition, pages
2011. Vol. 105, no 7, 927-936 p.
Tungstoenzyme, formaldehyde oxidoreductase, reaction mechanism, density functional theory, enzyme catalysis
IdentifiersURN: urn:nbn:se:su:diva-43038DOI: 10.1016/j.jinorgbio.2011.03.020ISI: 000291518700001OAI: oai:DiVA.org:su-43038DiVA: diva2:353211
FunderSwedish Research Council