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DFT Study of the Active Site of the XoxF‐Type Natural, Cerium‐Dependent Methanol Dehydrogenase Enzyme
Author(s) -
Bogart Justin A.,
Lewis Andrew J.,
Schelter Eric J.
Publication year - 2015
Publication title -
chemistry – a european journal
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.687
H-Index - 242
eISSN - 1521-3765
pISSN - 0947-6539
DOI - 10.1002/chem.201405159
Subject(s) - cerium , methanol dehydrogenase , chemistry , active site , pyrroloquinoline quinone , redox , inorganic chemistry , quinone , electrochemistry , saturated calomel electrode , methanol , catalysis , stereochemistry , enzyme , organic chemistry , cofactor , electrode , reference electrode
Rare‐earth metal cations have recently been demonstrated to be essential co‐factors for the growth of the methanotrophic bacterium Methylacidiphilum fumariolicum SolV. A crystal structure of the rare‐earth‐dependent methanol dehydrogenase (MDH) includes a cerium cation in the active site. Herein, the Ce–MDH active site has been analyzed through DFT calculations. The results show the stability of the Ce III –pyrroloquinoline quinone (PQQ) semiquinone configuration. Calculations on the active oxidized form of this complex indicate a 0.81 eV stabilization of the PQQ 0 LUMO at cerium versus calcium, supporting the observation that the cerium cation in the active site confers a competitive advantage to Methylacidiphilum fumariolicum SolV. Using reported aqueous electrochemical data, a semi‐empirical correlation was established based on cerium(IV/III) redox potentials. The correlation allowed estimation of the cerium oxidation potential of +1.35 V versus saturated calomel electrode (SCE) in the active site. The results are expected to guide the design of functional model complexes and alcohol‐oxidation catalysts based on lanthanide complexes of biologically relevant quinones.