title: A pathway for biosynthesis of divinyl ether fatty acids in green leaves.
abstract: [1-14C]alpha-Linolenic acid was incubated with a particulate fraction of homogenate of leaves of the meadow buttercup (Ranunculus acris L.). The main product was a divinyl ether fatty acid, which was identified as 12-[1'(Z),3'(Z)-hexadienyloxy]-9(Z),11(E)-dodecadienoic acid. Addition of glutathione peroxidase and reduced glutathione to incubations of alpha-linolenic acid almost completely suppressed formation of the divinyl ether acid and resulted in the appearance of 13(S)-hydroxy-9(Z), 11(E),15(Z)-octadecatrienoic acid as the main product. This result, together with the finding that 13(S)-hydroperoxy-9(Z), 11(E),15(Z)-octadecatrienoic acid served as an efficient precursor of the divinyl ether fatty acid, indicated that divinyl ether biosynthesis in leaves of R. acris occurred by a two-step pathway involving an omega6-lipoxygenase and a divinyl ether synthase. Incubations of isomeric hydroperoxides derived from alpha-linolenic and linoleic acids with the enzyme preparation from R. acris showed that 13(S)-hydroperoxy-9(Z),11(E)-octadecadienoic acid was transformed into the divinyl ether 12-[1'(Z)-hexenyloxy]-9(Z), 11(E)-dodecadienoic acid. In contrast, neither the 9(S)-hydroperoxides of linoleic or alpha-linolenic acids nor the 13(R)-hydroperoxide of alpha-linolenic acid served as precursors of divinyl ethers.
authors.affiliation: Department of Medical Biochemistry and Biophysics, Karolinska Institutet, Stockholm, Sweden. Mats.Hamberg@mbb.ki.se
authors.forename: M
authors.initials: M
authors.lastname: Hamberg
mesh_terms: D002734:Chlorophyll; D003116:Color; D003577:Cytochrome P-450 Enzyme System; D004987:Ethers / Q000378:metabolism*; D005231:Fatty Acids, Unsaturated / Q000096:biosynthesis* / Q000378:metabolism*; D008084:Lipoxygenase / Q000378:metabolism; D019684:Magnoliopsida / Q000378:metabolism; D010084:Oxidation-Reduction; D010088:Oxidoreductases / Q000378:metabolism; D018515:Plant Leaves / Q000378:metabolism*; D010940:Plant Proteins; D014753:Vinyl Compounds / Q000378:metabolism*; D017962:alpha-Linolenic Acid / Q000378:metabolism
chemical_list: C117640:12-(1',3'-hexadienyloxy)-9,11-dodecadienoic acid; D004987:Ethers; D005231:Fatty Acids, Unsaturated; D010940:Plant Proteins; D014753:Vinyl Compounds; C095608:etheroleic acid; D017962:alpha-Linolenic Acid; D002734:Chlorophyll; C100195:vinyl ether; C002946:colneleic acid; D003577:Cytochrome P-450 Enzyme System; D010088:Oxidoreductases; C100485:divinyl ether synthase; D008084:Lipoxygenase