Stereoselective oxidation of regioisomeric octadecenoic acids by fatty acid dioxygenases

Abstract

late systemic metabolic homeostasis, and it potentiates the effects of insulin ( 1, 2 ). Oleic acid modulates infl ammation, and both oleic acid and oleoylethanolamine suppress food intake ( 3-6 ). Mono-and polyunsaturated fatty acids can be oxygenated by P450, heme-dependent fatty acid dioxygenases, and lipoxygenases to a long list of biological mediators, eicosanoids, and oxylipins. Oxidation of arachidonic acid in humans and linoleic and ␣ -linolenic acids in plants has been studied extensively ( 7-10 ). In contrast to plants and animals, some microorganisms can also oxygenate monounsaturated fatty acids effi ciently to oxylipins of physiological interest ( 11,12 ).Enzymatic oxidation of octadecenoic acids to hydroperoxides has been reported in bacteria (e.g., Pseudomonas aeruginosa ) and fungi (e.g., Gaeumannomyces graminis , aspergilli). P. aeruginosa expresses a prominent enzyme in the periplasm that oxidizes oleic acid sequentially to (10 S )-hydroperoxy-(8 E )-octadecenoic acid (10 S -HpOME ) and (7 S ,10 S )-dihydroxy-(8 E )-octadecenoic acid ( 12 ). Oleic acid is oxidized by G. graminis and several aspergilli sequentially to (8 R )-hydroperoxyoleic acid (8 R -HpOME) and to diols, e.g., (7 S ,8 S )-dihydroxyoleic acid (7 S ,8 SDiHOME ) , 5 S ,8 R -DiHOME, and 8 R ,11 S -DiHOME ( 13-15 ). These oxylipins affect sexual and asexual sporulation in Aspergillus nidulans ( 14 ), and the key intermediate, 8 RHpOME, is formed by two closely related enzymes, linoleate diol synthases (LDS) and linoleate 10 R -dioxygenases (10 R -DOX). These enzymes belong to the group of animal heme peroxidases/myeloperoxidases that also include cyclooxygenases (COX) of animals and ␣ -DOX of plants ( 15, 16 ).Abstract Seven Z -octadecenoic acids having the double bond located in positions 6Z to 13Z were photooxidized. The resulting hydroperoxy-E -octadecenoic acids [HpOME( E )] were resolved by chiral phase-HPLC-MS, and the absolute confi gurations of the enantiomers were determined by gas chromatographic analysis of diastereoisomeric derivatives. The MS/MS/MS spectra showed characteristic fragments, which were infl uenced by the distance between the hydroperoxide and carboxyl groups. These fatty acids were then investigated as substrates of cyclooxygenase-1 (COX-1), manganese lipoxygenase (

Discovery of a linoleate 9S-dioxygenase and an allene oxide synthase in a fusion protein of Fusarium oxysporum

“…9-HPODE was prepared by photooxidation, purified by normal phase HPLC, and the S and R stereoisomers of 9-HPODE were partly separated on Reprosil Chiral NR-R ( 18,26 ); the latter contained a few percent of the S stereoisomer. 9 S -HPODE, 13 S-HPODE, 13 S -hydroperoxyoctadecatrienoic acid (HPOTrE), 13 R -HPODE, and 13 RHPOTrE were prepared enzymatically [tomato LOX ( 27 ), soybean LOX-1, and 13 R -MnLOX ( 28 )] and purifi ed by silica chromatography.…”

Expression of Fusion Proteins of Aspergillus terreus Reveals a Novel Allene Oxide Synthase

“…[ 13 C 18 ]18:2n-6 (98%) was from Larodan. HPODEs and HPOMEs were prepared by photooxidation and purified by NP-HPLC, and stereoisomers were separated on Reprosil Chiral NR-R (35). Mouse anti-V5 antibody, Superscript III kit, InsectSelect System with pIZ/V5-His, Cellfectin, phleomycin (Zeocin), and Champion pET Directional TOPO kit were from Invitrogen.…”

The biogeochemistry of lipid derived infochemical signals in the ocean

“…But LOX enzymes are specific for the cis, cis-1,4 pentadienes of polyunsaturated fatty acids and are not thought to oxidize monounsaturated fatty acids. However, linoleate diol synthase (LDS) from fungi can convert C16:1 free fatty acid to HHME and dihydroxy HHME in culture experiments (Garscha et al, 2007a;Oliw et al, 2011). PpoA/8,11-LDS enzyme in Aspergilus sp.…”