Formation of ketols from linolenic acid 13-hydroperoxide via allene oxide. Evidence for two distinct mechanisms of allene oxide hydrolysis

Grechkin, Alexander N.; Kuramshin, R. A.; Safonova, E.Y.; Latypov, Shamil K.; Il'yasov, A. V.

doi:10.1016/0005-2760(91)90176-i

Cited by 33 publications

(21 citation statements)

References 14 publications

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“…Interestingly, in cts2, the levels of 13-hydroxy-12-oxo-octadecadienoic acid (a-ketol) and 9-hydroxy-12-oxo-octadecadienoic acid (g-ketol) were elevated relative to the wild type. An increase in these compounds, which are formed by nonenzymic hydrolysis of unstable allene oxides (Grechkin et al, 1991), is indicative of an increased ability to oxidize 18:3 (Weber et al, 1997). In a previous report, a-ketol formation increased in response to dnOPDA treatment of Arabidopsis (Weber et al, 1997), suggesting that the increase in ketols in cts2 might reflect the elevated levels of OPDA in this mutant.…”

mentioning

confidence: 79%

Jasmonic Acid Levels Are Reduced in COMATOSE ATP-Binding Cassette Transporter Mutants. Implications for Transport of Jasmonate Precursors into Peroxisomes

Theodoulou

Job²,

Slocombe³

et al. 2005

Plant Physiology

245

191

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confidence: 79%

Jasmonic Acid Levels Are Reduced in COMATOSE ATP-Binding Cassette Transporter Mutants. Implications for Transport of Jasmonate Precursors into Peroxisomes

Theodoulou

Job²,

Slocombe³

et al. 2005

Plant Physiology

245

191

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“…Ref. 36). Using methods we have developed for the biosynthesis, isolation, and HPLC of highly unstable epoxides, we prepared the intermediate by incubation and simultaneous extraction of 12R-HPOTrE with the full-length fusion protein at 0°C and HPLC-purified the methyl ester derivative at subzero temperature (Ϫ15°C, Fig.…”

Section: Analysis Of the Epoxide Stereoconfiguration In The Linoleic mentioning

confidence: 99%

Evidence for an Ionic Intermediate in the Transformation of Fatty Acid Hydroperoxide by a Catalase-related Allene Oxide Synthase from the Cyanobacterium Acaryochloris marina

Gao

Boeglin

Zheng

et al. 2009

Journal of Biological Chemistry

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Allene oxides are reactive epoxides biosynthesized from fatty acid hydroperoxides by specialized cytochrome P450s or by catalase-related hemoproteins. Here we cloned, expressed, and characterized a gene encoding a lipoxygenase-catalase/peroxidase fusion protein from Acaryochloris marina. We identified novel allene oxide synthase (AOS) activity and a by-product that provides evidence of the reaction mechanism. The fatty acids 18.43 and 18.33 are oxygenated to the 12R-hydroperoxide by the lipoxygenase domain and converted to the corresponding 12R,13-epoxy allene oxide by the catalase-related domain. Linoleic acid is oxygenated to its 9R-hydroperoxide and then, surprisingly, converted ϳ70% to an epoxyalcohol identified spectroscopically and by chemical synthesis as 9R,10S-epoxy-13S-hydroxyoctadeca-11E-enoic acid and only ϳ30% to the 9R,10-epoxy allene oxide. Experiments using oxygen-18-labeled 9R-hydroperoxide substrate and enzyme incubations conducted in H A diverse spectrum of signaling molecules is biosynthesized in nature from polyunsaturated fatty acids, their peroxides, and further transformations of the fatty acid peroxides. The peroxides are formed by two classes of dioxygenase enzyme. The hemoprotein dioxygenases include prostaglandin H synthase (cyclooxygenase) in animals (1), ␣-dioxygenase in plants (2), and several linoleate dioxygenases in fungi (3-5). The nonheme iron lipoxygenases are even more widespread, being almost ubiquitous among organisms that contain polyunsaturated fatty acids (6 -8). Although further biosynthetic transformation is sometimes accomplished by an additional catalytic activity of the initiating dioxygenase (e.g. leukotriene A 4 synthase (9) or aldehyde-synthesizing hydroperoxide cleaving activity (10) among the LOX 2 enzymes), commonly another distinct enzyme is used to rearrange or otherwise modify the reactive fatty acid peroxide intermediate. Two hemoprotein types are found that have become specialized for this biosynthetic role: cytochrome P450s and catalase-related enzymes.The fatty acid peroxide-metabolizing P450s are by far the better known and include CYP5 (thromboxane synthase) and CYP8A (prostacyclin synthase) in animals (11), and the entire family of CYP74 in plants (12). The individual CYP74 enzymes include allene oxide synthase (AOS), one of which catalyzes a key step in cyclopentenone synthesis in the jasmonate pathway, hydroperoxide lyase, divinyl ether synthase, and epoxyalcohol synthase (12, 13). The catalase-related enzymes are distinctive in that they have been found naturally as a fusion protein with the LOX enzyme that forms their hydroperoxide substrate (14). The known activities include AOS in Plexaura homomalla and other marine corals (with a different specificity for fatty acid hydroperoxide compared with the plant P450 AOS) (15,16), and the unique bicyclobutane synthase and other allylic epoxide synthase activities of the enzyme in the cyanobacterium Anabaena 18). Currently we are trying to understand the scope of the reactions catalyzed by this catala...

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“…[1-t4C](9Z, 11 E, 13S)-13-Hydrop eroxy-9,11-octadecadienoic acid (13-HPOD) and [1-~4C]-(9Z,11E,13S,15Z )-13-hydroperoxy-9,11,15-octadecatrienoic acid (13-HPOT) were prepared by incubations of linoleic and linolenic acids, respectively, with soybean lipoxygenase as described previously [8,9]. [1-14C]9-HPOD and [1-14C]9-HPOT were obtained by incubations of linoleate and linolenate, respectively, with potato tuber lipoxygenase as described in [7,9].…”

Section: Substrate Preparationsmentioning

confidence: 99%

“…The extracted products were methylated with ethereal diazomethane. Radio-HPLC analyses were performed in main details as described previously [7][8][9]. The obtained methyl esters were separated by the reversed-phase radio-HPLC on the OctadecylDaltosil 100 (5/lm, 4.6 × 250 mm; Serva Feinbiochemica, Heidelberg, Germany) column using linear gradient from 60 : 40 to 96 : 4 (v/v) in the solvent mixture methanol/water for 55 min, then 25 min more in isocratic conditions, flow rate 0.4 ml/min.…”

Section: Extraction and Analysand Of Productsmentioning

confidence: 99%

The lipoxygenase pathway in garlic (Allium sativum L.) bulbs: detection of the novel divinyl ether oxylipins

1995

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Formation of ketols from linolenic acid 13-hydroperoxide via allene oxide. Evidence for two distinct mechanisms of allene oxide hydrolysis

Cited by 33 publications

References 14 publications

Jasmonic Acid Levels Are Reduced in COMATOSE ATP-Binding Cassette Transporter Mutants. Implications for Transport of Jasmonate Precursors into Peroxisomes

Jasmonic Acid Levels Are Reduced in COMATOSE ATP-Binding Cassette Transporter Mutants. Implications for Transport of Jasmonate Precursors into Peroxisomes

Evidence for an Ionic Intermediate in the Transformation of Fatty Acid Hydroperoxide by a Catalase-related Allene Oxide Synthase from the Cyanobacterium Acaryochloris marina

The lipoxygenase pathway in garlic (Allium sativum L.) bulbs: detection of the novel divinyl ether oxylipins

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