title: Formation of halogenated medium chain hydrocarbons by a lipoxygenase/hydroperoxide halolyase-mediated transformation in planktonic microalgae.
abstract: A rapid transformation of eicosapentaenoic acid is initiated upon disintegration of cells of the marine diatom Stephanopyxis turris. In contrast to any other fatty acid cleaving activity known, this diatom releases a blend of chlorinated C8 hydrocarbons in addition to an unsaturated 12-oxo acid. Using labeled precursors, trapping experiments, and selective inhibition of enzyme activities, we were able to show that a lipoxygenase activates the C20 fatty acid to a hydroperoxide, which is subsequently cleaved by a new hydroperoxide halolyase to the C8 and C12 products. This adds a fundamentally new pathway to the limited set of halogenating enzymatic activities known from nature.
authors.affiliation: Institute of Chemical Sciences and Engineering, Ecole Polytechnique Fédérale de Lausanne (EPFL), CH-1015 Lausanne, Switzerland.
authors.forename: Thomas
authors.initials: T
authors.lastname: Wichard
authors.forename: Georg
authors.initials: G
authors.lastname: Pohnert
mesh_terms: D000446:Aldehyde-Lyases / Q000378:metabolism*; D002853:Chromatography, Liquid; D003577:Cytochrome P-450 Enzyme System / Q000378:metabolism*; D017377:Diatoms / Q000201:enzymology / Q000378:metabolism; D015777:Eicosanoids / Q000378:metabolism*; D006846:Hydrocarbons, Halogenated / Q000737:chemistry / Q000378:metabolism*; D008084:Lipoxygenase / Q000378:metabolism*; D015394:Molecular Structure; D010839:Phytoplankton / Q000201:enzymology / Q000378:metabolism; D021241:Spectrometry, Mass, Electrospray Ionization
chemical_list: D015777:Eicosanoids; D006846:Hydrocarbons, Halogenated; D003577:Cytochrome P-450 Enzyme System; D008084:Lipoxygenase; D000446:Aldehyde-Lyases; C054540:hydroperoxide lyase