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Manganese lipoxygen...
Manganese lipoxygenase oxidizes bis-allylic hydroperoxides and octadecenoic acids by different mechanisms
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- Oliw, Ernst H., 1948- (författare)
- Uppsala universitet,Institutionen för farmaceutisk biovetenskap,Biokemisk farmakologi
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- Jernerén, Fredrik (författare)
- Uppsala universitet,Institutionen för farmaceutisk biovetenskap,Biokemisk farmakologi
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- Hoffmann, Inga, 1984- (författare)
- Uppsala universitet,Institutionen för farmaceutisk biovetenskap,Biokemisk farmakologi
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- Sahlin, Margareta (författare)
- Stockholms universitet,Institutionen för molekylärbiologi och funktionsgenomik,Molekylärbiologi, Stockholms universitet
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- Garscha, Ulrike (författare)
- Uppsala universitet,Institutionen för farmaceutisk biovetenskap,Biokemisk farmakologi
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(creator_code:org_t)
- Elsevier BV, 2011
- 2011
- Engelska.
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Ingår i: Biochimica et Biophysica Acta - Molecular and Cell Biology of Lipids. - : Elsevier BV. - 1388-1981 .- 1879-2618. ; 1811:3, s. 138-147
- Relaterad länk:
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https://urn.kb.se/re...
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https://doi.org/10.1...
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https://urn.kb.se/re...
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Abstract
Ämnesord
Stäng
- Manganese lipoxygenase (MnLOX) oxidizes (11R)-hydroperoxylinolenic acid (11R-HpOTrE) to a peroxyl radical. Our aim was to compare the enzymatic oxidation of 11R-HpOTrE and octadecenoic acids with LOO-H and allylic C-H bond dissociation enthalpies of ~88 and ~87kcal/mol. Mn(III)LOX oxidized (11Z)-, (12Z)-, and (13Z)-18:1 to hydroperoxides with R configuration, but this occurred at insignificant rates (<1%) compared to 11R-HpOTrE. We next examined whether transitional metals could mimic this oxidation. Ce(4+) and Mn(3+) transformed 11R-HpOTrE to hydroperoxides at C-9 and C-13 via oxidation to a peroxyl radical at C-11, whereas Fe(3+) was a poor catalyst. Our results suggest that MnLOX oxidizes bis-allylic hydroperoxides to peroxyl radicals in analogy with Ce(4+) and Mn(3+). The enzymatic oxidation likely occurs by proton-coupled electron transfer of the electron from the hydroperoxide anion to Mn(III) and H(+) to the catalytic base, Mn(III)OH(-). Hydroperoxides abolish the kinetic lag times of MnLOX and FeLOX by oxidation of their metal centers, but 11R-HpOTrE was isomerized by MnLOX to (13R)-hydroperoxy-(9Z,11E,15Z)-octadecatrienoic acid (13R-HpOTrE) with a kinetic lag time. This lag time could be explained by two competing transformations, dehydration of 11R-HpOTrE to 11-ketolinolenic acid and oxidation of 11R-HpOTrE to peroxyl radical; the reaction rate then increases as 13R-HpOTrE oxidizes MnLOX with subsequent formation of two epoxyalcohols. We conclude that oxidation of octadecenoic acids and bis-allylic hydroperoxides occurs by different mechanisms, which likely reflect the nature of the hydrogen bonds, steric factors, and the redox potential of the Mn(III) center.
Ämnesord
- MEDICIN OCH HÄLSOVETENSKAP -- Medicinsk bioteknologi -- Medicinsk bioteknologi (hsv//swe)
- MEDICAL AND HEALTH SCIENCES -- Medical Biotechnology -- Medical Biotechnology (hsv//eng)
- NATURVETENSKAP -- Biologi (hsv//swe)
- NATURAL SCIENCES -- Biological Sciences (hsv//eng)
Nyckelord
- Proton coupled electron transfer
- fatty acid oxidation
- PGH synthase
- mass spectrometry
- redox chemistry
- Biochemistry
- Biokemi
- Biochemical Pharmacology
- Biokemisk farmakologi
Publikations- och innehållstyp
- ref (ämneskategori)
- art (ämneskategori)
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