title: Decarboxylation of fatty acids to terminal alkenes by cytochrome P450 compound I.
abstract: OleT(JE), a cytochrome P450, catalyzes the conversion of fatty acids to terminal alkenes using hydrogen peroxide as a cosubstrate. Analytical studies with an eicosanoic acid substrate show that the enzyme predominantly generates nonadecene and that carbon dioxide is the one carbon coproduct of the reaction. The addition of hydrogen peroxide to a deuterated substrate-enzyme (E-S) complex results in the transient formation of an iron(IV) oxo π cation radical (Compound I) intermediate which is spectroscopically indistinguishable from those that perform oxygen insertion chemistries. A kinetic isotope effect for Compound I decay suggests that it abstracts a substrate hydrogen atom to initiate fatty acid decarboxylation. Together, these results indicate that the initial mechanism for alkene formation, which does not result from oxygen rebound, is similar to that widely suggested for P450 monooxygenation reactions.
authors.affiliation: Department of Chemistry and Biochemistry, University of South Carolina, Columbia, South Carolina 29208, United States.
authors.forename: Job L
authors.initials: JL
authors.lastname: Grant
authors.affiliation: Department of Chemistry and Biochemistry, University of South Carolina, Columbia, South Carolina 29208, United States.
authors.forename: Chun H
authors.initials: CH
authors.lastname: Hsieh
authors.affiliation: Department of Chemistry and Biochemistry, University of South Carolina, Columbia, South Carolina 29208, United States.
authors.forename: Thomas M
authors.initials: TM
authors.lastname: Makris
mesh_terms: D000475:Alkenes / Q000737:chemistry / Q000378:metabolism*; D003577:Cytochrome P-450 Enzyme System / Q000737:chemistry / Q000378:metabolism*; D003653:Decarboxylation; D005227:Fatty Acids / Q000737:chemistry / Q000378:metabolism*; D015394:Molecular Structure
chemical_list: D000475:Alkenes; D005227:Fatty Acids; D003577:Cytochrome P-450 Enzyme System