13-hydroperoxylinolenic-acid and linoleic-acid-hydroperoxide

13-hydroperoxylinolenic-acid has been researched along with linoleic-acid-hydroperoxide* in 3 studies

Other Studies

3 other study(ies) available for 13-hydroperoxylinolenic-acid and linoleic-acid-hydroperoxide

ArticleYear
Identification of an allene oxide synthase (CYP74C) that leads to formation of alpha-ketols from 9-hydroperoxides of linoleic and linolenic acid in below-ground organs of potato.
    The Plant journal : for cell and molecular biology, 2006, Volume: 47, Issue:6

    Allene oxide synthase (AOS) enzymes are members of the cytochrome P450 enzyme family, sub-family CYP74. Here we describe the isolation of three cDNAs encoding AOS from potato (StAOS1-3). Based on sequence comparisons, they represent members of either the CYP74A (StAOS1 and 2) or the CYP74C (StAOS3) sub-families. StAOS3 is distinguished from the other two AOS isoforms in potato by its high substrate specificity for 9-hydroperoxides of linoleic and linolenic acid, compared with 13-hydroperoxides, which are only poor substrates. The highest activity was shown with (9S,10E,12Z)-9-hydroperoxy-10,12-octadecadienoic acid (9-HPODE) as a substrate. This hydroperoxide was metabolized in vitro to alpha- and gamma-ketols as well as to the cyclopentenone compound 10-oxo-11-phytoenoic acid. They represent hydrolysis products of the initial StAOS3 product 9,10-epoxyoctadecadienoic acid, an unstable allene oxide. By RNA gel hybridization blot analysis, StAOS3 was shown to be expressed in sprouting eyes, stolons, tubers and roots, but not in leaves. StAOS3 protein was found in all organs tested, but mainly in stems, stolons, sprouting eyes and tubers. As in vivo reaction products, the alpha-ketols derived from 9-hydroperoxides of linoleic and linolenic acid were only found in roots, tubers and sprouting eyes. Immunolocalization showed that StAOS3 was associated with amyloplasts and leucoplasts.

    Topics: Base Sequence; Blotting, Western; DNA Primers; Immunohistochemistry; Intramolecular Oxidoreductases; Linoleic Acids; Linolenic Acids; Lipid Peroxides; Nucleic Acid Hybridization; Reverse Transcriptase Polymerase Chain Reaction; RNA, Messenger; Solanum tuberosum; Subcellular Fractions

2006
Catalytic properties of allene oxide synthase from flaxseed (Linum usitatissimum L.).
    Lipids, 1998, Volume: 33, Issue:2

    We investigated the catalytic and kinetic properties of allene oxide synthase (AOS; E.C. 4.2.1.92) from flaxseed (Linum usitatissimum L.). Both Michaelis constant and maximal initial velocity for the conversion of 9(S)- and 13(S)-hydroperoxides of linoleic and linolenic acid were determined by a photometric assay. 13(S)-Hydroperoxy-9(Z), 11(E)-octadecadienoic acid [13(S)-HPOD] as the most effective substrate was converted at 116.9 +/- 5.8 nkat/mg protein by the flax enzyme extract. The enzyme was also incubated with a series of variable conjugated hydroperoxy dienyladipates. Substrates with a shape similar to the natural hydroperoxides showed the best reactivity. Monoenoic substrates as oleic acid hydroperoxides were not converted by the enzyme. In contrast, 12-hydroperoxy-9(Z), 13(E)-octadecadienoic acid was a strong competitive inhibitor for AOS catalyzed degradation of 13(S)-HPOD. The inhibitor constant was determined to be 0.09 microM. Based on these results, we concluded that allene oxide synthase requires conjugated diene hydroperoxides for successful catalysis. Studying the enantiomeric preference of the enzyme, we found that AOS was also able to metabolize (R)-configurated fatty acid hydroperoxides. Conversion of these substrates into labile allene oxides was confirmed by steric analysis of the stable alpha-ketol hydrolysis products.

    Topics: Flax; Intramolecular Oxidoreductases; Linoleic Acids; Linolenic Acids; Lipid Peroxides; Seeds; Stereoisomerism; Substrate Specificity

1998
Amperometric determination of lipid hydroperoxides.
    Analytical biochemistry, 1995, Mar-01, Volume: 225, Issue:2

    A new amperometric analytical technique for measuring lipid hydroperoxides is described. The technique is based on the measurement of cathodic current due to the reduction of ferricinium ion formed as result of the oxidation of ferrocene by lipid hydroperoxides. The effects of pH and applied potential were investigated to determine the optimum pH and working potential for the determination of linoleic acid and linolenic acid hydroperoxides. The analysis, performed in pH 5.5, 0.1 M phosphate buffer and at -100 mV (vs Ag/AgCl) applied potential, responded linearly to linoleic acid hydroperoxide and linolenic acid hydroperoxide up to 1.5 and 1.2 microM, respectively. The lower detection limits were 20 nM for linoleic acid hydroperoxide and 25 nM for linolenic acid hydroperoxide. Reductants such as ascorbate and urate present in the biological samples, as well as other peroxides, did not interfere in the amperometric analyses of lipid hydroperoxides.

    Topics: Ascorbic Acid; Chemical Phenomena; Chemistry, Physical; Electric Conductivity; Electrochemistry; Electrodes; Ferrous Compounds; Hydrogen-Ion Concentration; Linoleic Acids; Linolenic Acids; Lipid Peroxides; Metallocenes; Organometallic Compounds; Oxidation-Reduction; Oxygen; Sensitivity and Specificity; Spectrophotometry; Uric Acid

1995
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