Transient inverted metastable iron hydroperoxides in fenton chemistry. A nonenzymatic model for cytochrome p450 hydroxylation.
Quantum mechanical calculations (DFT) have provided a mechanism for the oxidative C-H bond cleavage step in Fenton-like hydrocarbon hydroxylation. A transition structure for hydrocarbon oxidation by aqueous solvated cationic iron(III) hydroperoxides ((H(2)O)(n)Fe(III)OOH) is presented that involves a novel rearrangement of the hydroperoxide group (FeO-OH --> FeO...HO) in concert with hydrogen abstraction by the incipient HO* radical with activation barriers ranging from 17 to 18 kcal/mol. In every hydroperoxide examined, the activation barrier for FeO-OH isomerization, in the absence of the hydrocarbon, is significantly greater than the overall concerted activation barrier for C-H bond cleavage in support of the concept of O-O bond isomerization in concert with hydrogen abstraction. The transition structure for the oxidation step in simple anionic iron(III) hydroperoxides has been shown to bear a remarkable resemblance to model porphyrin calculations on cytochrome P450 hydroxylation.
Bach
Robert D
RD
Department of Chemistry and Biochemistry, University of Delaware, Newark, Delaware 19716, USA. rbach@udel.edu
Dmitrenko
Olga
O
D003577:Cytochrome P-450 Enzyme System / Q000737:chemistry*; D005290:Ferric Compounds / Q000737:chemistry*; D006861:Hydrogen Peroxide / Q000737:chemistry*; D006900:Hydroxylation; D007501:Iron / Q000737:chemistry*; D010084:Oxidation-Reduction; D011166:Porphyrins / Q000737:chemistry; D011789:Quantum Theory; D013816:Thermodynamics
C045076:Fenton's reagent; D005290:Ferric Compounds; D011166:Porphyrins; D003577:Cytochrome P-450 Enzyme System; D006861:Hydrogen Peroxide; D007501:Iron