title: First principles investigation of singly reduced cytochrome P450.
abstract: 1. The application of novel ab initio quantum mechanical methods to the states in the catalytic cycle of cytochrome P450 following the first reduction step is described. 2. A good correlation was found between the calculated energy of reduction and the experimentally determined redox potential for a range of substrate- and substrate analogue-bound systems. 3. On reduction of the haem system, the ground state of Fe remains Fe3+. On binding of a CO molecule, Fe adopts a low-spin Fe2+ state, in agreement with experiment. However, on binding of an O2 molecule, calculations indicate that the system adopts a ferric superoxide ground state, in which the Fe is in a low-spin Fe3+ state.
authors.affiliation: Cavendish Laboratory (TCM), University of Cambridge, UK. mds21@phy.cam.ac.uk
authors.forename: M D
authors.initials: MD
authors.lastname: Segall
authors.forename: M C
authors.initials: MC
authors.lastname: Payne
authors.forename: S W
authors.initials: SW
authors.lastname: Ellis
authors.forename: G T
authors.initials: GT
authors.lastname: Tucker
authors.forename: P J
authors.initials: PJ
authors.lastname: Eddershaw
mesh_terms: D019475:Camphor 5-Monooxygenase / Q000737:chemistry / Q000378:metabolism*; D003198:Computer Simulation; D004734:Energy Metabolism; D006418:Heme / Q000737:chemistry / Q000378:metabolism; D007501:Iron / Q000737:chemistry / Q000378:metabolism; D008958:Models, Molecular; D010084:Oxidation-Reduction; D016958:Pseudomonas putida / Q000201:enzymology; D011789:Quantum Theory
chemical_list: D006418:Heme; D007501:Iron; D019475:Camphor 5-Monooxygenase