title: Hexadecanoid pathway in plants: Lipoxygenase dioxygenation of (7Z,10Z,13Z)-hexadecatrienoic acid.
abstract: 7,10,13-Hexadecatrienoic acid (16:3) is abundant in many plant species. However, its metabolism through the lipoxygenase pathway is not sufficiently understood. The goal of present work was to investigate the oxygenation of 16:3 by different plant lipoxygenases and to study the occurrence of oxygenated derivatives of 16:3 in plant seedlings. The recombinant maize 9-lipoxygenase specifically converted 16:3 into (7S)-hydroperoxide. Identification of this novel oxylipin was substantiated by data of GC-MS, LC-MS/MS, 1H-NMR, and 2D-COSY as well as by deuterium labeling from [(2)H(6)]16:3. Soybean lipoxygenase 1 produced 91% (11S)-hydroperoxide and 6% racemic 14-hydroperoxide. Recombinant soybean lipoxygenase 2 (specifically oxidizing linoleate into 13-hydroperoxide) lacked any specificity towards 16:3. Lipoxygenase 2 produced 7-, 8-, 10-, 11-, 13-, and 14-hydroperoxides of 16:3, as well as a significant amount of bis-allylic 9-hydroperoxide. Seedlings of several examined plant species possessed free hydroxy derivatives of 16:3 (HHTs), as well as their ethyl esters. Interestingly, HHTs occur not only in "16:3 plants", but also in typical "18:3 plants" like pea and soybean seedlings.
authors.affiliation: Kazan Institute of Biochemistry and Biophysics, Kazan Research Center, Russian Academy of Sciences, Russia.
authors.forename: E V
authors.initials: EV
authors.lastname: Osipova
authors.forename: N V
authors.initials: NV
authors.lastname: Lantsova
authors.forename: I R
authors.initials: IR
authors.lastname: Chechetkin
authors.forename: F K
authors.initials: FK
authors.lastname: Mukhitova
authors.forename: M
authors.initials: M
authors.lastname: Hamberg
authors.forename: A N
authors.initials: AN
authors.lastname: Grechkin
mesh_terms: D002851:Chromatography, High Pressure Liquid; D005231:Fatty Acids, Unsaturated / Q000737:chemistry / Q000378:metabolism*; D008401:Gas Chromatography-Mass Spectrometry; D008084:Lipoxygenase / Q000235:genetics / Q000378:metabolism*; D009682:Magnetic Resonance Spectroscopy; D054883:Oxylipins / Q000737:chemistry; D019308:Palmitic Acid / Q000378:metabolism*; D010944:Plants / Q000201:enzymology*; D011994:Recombinant Proteins / Q000235:genetics / Q000378:metabolism; D013025:Glycine max / Q000201:enzymology; D013237:Stereoisomerism; D013379:Substrate Specificity; D053719:Tandem Mass Spectrometry; D003313:Zea mays / Q000201:enzymology
chemical_list: C553093:7,10,13-hexadecatrienoic acid; D005231:Fatty Acids, Unsaturated; D054883:Oxylipins; D011994:Recombinant Proteins; D019308:Palmitic Acid; D008084:Lipoxygenase