title: Cytochrome P450: an investigation of the Mössbauer spectra of a reaction intermediate and an Fe(IV)[double bond]O model system.
abstract: We have carried out a series of density functional theory (DFT) calculations to predict the 57Fe Mössbauer quadrupole splittings (DeltaEQ) and isomer shifts (deltaFe) for an Fe(IV)=O model compound ([Fe(O)(TMC)(NCCH3)](OTf)2, TMC = 1,4,8,11-tetramethyl-1,4,8,11-tetraazacyclotetradecane, OTf = CF3SO3-) as well as a cytochrome P450 reaction intermediate (P450-RI). The DFT predictions on the model compound are in almost exact agreement with experiment. The same DFT methods did not enable the prediction of the experimental DeltaEQ results for P450-RI when using the experimental protein crystal structure and seven different spin/charge/protonation state combinations, but did permit good predictions of both DeltaEQ and deltaFe when using a geometry optimized structure having a porphyrin dianion, a protonated cysteine, and S = 1 (the same as that found from previous ESR studies).
authors.affiliation: Department of Chemistry, University of Illinois at Urbana-Champaign, 600 South Mathews Avenue, Urbana, Illinois 61801, USA.
authors.forename: Yong
authors.initials: Y
authors.lastname: Zhang
authors.forename: Eric
authors.initials: E
authors.lastname: Oldfield
mesh_terms: D003577:Cytochrome P-450 Enzyme System / Q000737:chemistry* / Q000378:metabolism; D007501:Iron / Q000737:chemistry*; D008956:Models, Chemical; D010084:Oxidation-Reduction; D010087:Oxides / Q000737:chemistry; D015204:Spectroscopy, Mossbauer / Q000379:methods
chemical_list: D010087:Oxides; C066317:ferryl iron; D003577:Cytochrome P-450 Enzyme System; D007501:Iron