DFT Study of the Active Site of the XoxF-Type Natural, Cerium-Dependent Methanol Dehydrogenase Enzyme.

Bogart, Justin A.; Lewis, Andrew J.; Schelter, Eric J.

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 CeIII-pyrroloquinoline quinone (PQQ) semiquinone configuration. Calculations on the active oxidized form of this complex indicate a 0.81 eV stabilization of the PQQ0 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.

METHANOL dehydrogenase; CRYSTAL structure; DENSITY functional theory; SEMIQUINONE; CALOMEL

Chemistry - A European Journal, 2015, Vol 21, Issue 4, p1743

0947-6539

Academic Journal

10.1002/chem.201405159