On the mechanism of biosynthesis of divinyl ether oxylipins by enzyme from garlic bulbs.
The microsomal fraction of homogenate of garlic (Allium sativum L.) bulbs contains a divinyl ether synthase which catalyzes conversion of (9Z,11E,13S)-13-hydroperoxy-9, 11-octadecadienoic acid and (9Z,11E,13S,15Z)-13-hydroperoxy-9,11,15-octadecatri eno ic acid into (9Z,11E,1'E,)-12-(1'-hexenyloxy)-9,11-dodecadienoic acid (etherolenic acid) and (9Z,11E,1'E,3'Z)-12-(1',3'-hexadienyloxy)-9,11-dode cadienoic acid (etherolenic acid), respectively. Two isomers of etherolenic acid were isolated. As shown by NMR spectrometry, the double bond configurations of these compounds were (9E,11E,1'E) and (9Z,11Z,1'E). Experiments with linoleic acid (13R,S)-hydroperoxide demonstrated that the S enantiomer was a much better substrate for the divinyl ether synthase compared to the R enantiomer. Incubation of (9Z,11E,13S)-[18O2]hydroperoxy-9,11-octadecadienoic acid led to the formation of etherolenic acid which retained 18O in the ether oxygen. An intermediary role of an epoxyallylic cation in etherolenic acid biosynthesis is postulated.
Grechkin
A N
AN
Institute of Biology, Russian Academy of Sciences, Kazan, Russia.
Ilyasov
A V
AV
Hamberg
M
M
D002851:Chromatography, High Pressure Liquid; D003577:Cytochrome P-450 Enzyme System; D005231:Fatty Acids, Unsaturated / Q000096:biosynthesis*; D005737:Garlic / Q000201:enzymology*; D007536:Isomerism; D015289:Leukotrienes / Q000378:metabolism; D008041:Linoleic Acids / Q000378:metabolism; D008054:Lipid Peroxides / Q000378:metabolism; D009682:Magnetic Resonance Spectroscopy; D008861:Microsomes / Q000201:enzymology; D010088:Oxidoreductases / Q000378:metabolism*; D010940:Plant Proteins; D010946:Plants, Medicinal; D013379:Substrate Specificity
D005231:Fatty Acids, Unsaturated; D015289:Leukotrienes; D008041:Linoleic Acids; D008054:Lipid Peroxides; D010940:Plant Proteins; C095608:etheroleic acid; C038649:13-hydroperoxy-9,11-octadecadienoic acid; C002946:colneleic acid; C025086:15-hydroperoxy-5,8,11,13-eicosatetraenoic acid; D003577:Cytochrome P-450 Enzyme System; D010088:Oxidoreductases; C100485:divinyl ether synthase