Mechanism of reaction of myoglobin with the lipid hydroperoxide hydroperoxyoctadecadienoic acid

Reeder, J. Brandon; Wilson, Tyree

doi:10.1042/bj3301317

Cited by 72 publications

(62 citation statements)

References 33 publications

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“…It is often suggested in the literature that two such epoxyallylic peroxyl radicals in solution would combine by the Russell mechanism to give epoxyketone, epoxyalcohol, and singlet oxygen (42) or that the epoxyallylic peroxyl radical would transfer an oxygen atom to certain susceptible compounds (e.g. to epoxidize a double bond) with itself being con- verted to an epoxyalcohol (13,43).…”

Section: Discussionmentioning

confidence: 99%

On the Role of Molecular Oxygen in Lipoxygenase Activation

Zheng

Brash

2010

Journal of Biological Chemistry

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The oxygenation of polyunsaturated fatty acids by lipoxygenases (LOX) is associated with a lag phase during which the resting ferrous enzyme is converted to the active ferric form by reaction with fatty acid hydroperoxide. Epidermal lipoxygenase-3 (eLOX3) is atypical in displaying hydroperoxide isomerase activity with fatty acid hydroperoxides through cycling of the ferrous enzyme. Yet eLOX3 is capable of dioxygenase activity, albeit with a long lag phase and need for high concentrations of hydroperoxide activator. Here, we show that higher O 2 concentration shortens the lag phase in eLOX3, although it reduces the rate of hydroperoxide consumption, effects also associated with an A451G mutation known to affect the disposition of molecular oxygen in the LOX active site. These observations are consistent with a role of O 2 in interrupting hydroperoxide isomerase cycling. Activation of eLOX3, A451G eLOX3, and soybean LOX-1 with 13-hydroperoxy-linoleic acid forms oxygenated end products, which we identified as 9R-and 9S-hydroperoxy-12S,13S-trans-epoxyoctadec-10E-enoic acids. We deduce that activation partly depends on reaction of O 2 with the intermediate of hydroperoxide cleavage, the epoxyallylic radical, giving an epoxyallylic peroxyl radical that does not further react with Fe(III)-OH; instead, it dissociates and leaves the enzyme in the activated free ferric state. eLOX3 differs from soybean LOX-1 in more tightly binding the epoxyallylic radical and having limited access to O 2 within the active site, leading to a deficiency in activation and a dominant hydroperoxide isomerase activity.

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Section: Discussionmentioning

confidence: 99%

On the Role of Molecular Oxygen in Lipoxygenase Activation

Zheng

Brash

2010

Journal of Biological Chemistry

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“…Kinetics of lipid conjugated diene formation was followed at 234 nm, and the amount of conjugated diene formed was calculated from a three-point baseline drop from absorbance at 220 and 250 nm (Abs 234 − (0.533 × Abs 220 + 0.467 × Abs 250 )). The extinction coefficient for conjugated diene at 234 nm was 2.5 × 10 4 M −1 cm −122 as calculated from a known concentration of 13-S-hydroperoxy 9-cis, 11-trans octadecadienoic acid prepared from the peroxidation of linoleic acid by soybean lipoxygenase, 23 or 1.1 × 10 4 M −1 cm −1 using the baseline drop method.…”

Section: Methodsmentioning

confidence: 99%

“…Conjugated dienes are formed, following free radical mediated oxidation, from the rearrangement of carbon double bond systems, such as the 1,4 cis−cis pentadiene (found in unsaturated lipids like linoleate and arachidonate). 22,23 This conjugation can be used as a marker for lipid oxidation. We used CP20 as the reductant because CP20, in contrast to ascorbate, did not cause any significant reduction of the ferric Mb to the ferrous oxidation state over time scales used for the lipid oxidation experiment.…”

Section: Tyrosine Redoxmentioning

confidence: 99%

Engineering Tyrosine-Based Electron Flow Pathways in Proteins: The Case of Aplysia Myoglobin

et al. 2012

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Tyrosine residues can act as redox cofactors that provide an electron transfer ("hole-hopping") route that enhances the rate of ferryl heme iron reduction by externally added reductants, for example, ascorbate. Aplysia fasciata myoglobin, having no naturally occurring tyrosines but 15 phenylalanines that can be selectively mutated to tyrosine residues, provides an ideal protein with which to study such through-protein electron transfer pathways and ways to manipulate them. Two surface exposed phenylalanines that are close to the heme have been mutated to tyrosines (F42Y, F98Y). In both of these, the rate of ferryl heme reduction increased by up to 3 orders of magnitude. This result cannot be explained in terms of distance or redox potential change between donor and acceptor but indicates that tyrosines, by virtue of their ability to form radicals, act as redox cofactors in a new pathway. The mechanism is discussed in terms of the Marcus theory and the specific protonation/deprotonation states of the oxoferryl iron and tyrosine. Tyrosine radicals have been observed and quantified by EPR spectroscopy in both mutants, consistent with the proposed mechanism. The location of each radical is unambiguous and allows us to validate theoretical methods that assign radical location on the basis of EPR hyperfine structure. Mutation to tyrosine decreases the lipid peroxidase activity of this myoglobin in the presence of low concentrations of reductant, and the possibility of decreasing the intrinsic toxicity of hemoglobin by introduction of these pathways is discussed.

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“…The 13(S)-hydroperoxides were prepared by enzymatic reaction of lipoxygenase with methyl linoleate or methyl linolenate (16). Mixtures of lipid hydroperoxides were prepared by incubation of 10 mM methyl linoleate or 10 mM methyl linolenate with 25 mM ascorbate and 0.1 mM FeCl 3 in 50 mM Hepes buffer, pH 7.2, at 37°C for 2 hr.…”

Section: Methodsmentioning

confidence: 99%

Modifications of proteins by polyunsaturated fatty acid peroxidation products

Refsgaard

Tsai²,

Stadtman³

2000

Proc. Natl. Acad. Sci. U.S.A.

296

195

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The ability of unsaturated fatty acid methyl esters to modify amino acid residues in bovine serum albumin (BSA), glutamine synthetase, and insulin in the presence of a metal-catalyzed oxidation system [ascorbate͞Fe(III)͞O2] depends on the degree of unsaturation of the fatty acid. The fatty acid-dependent generation of carbonyl groups and loss of lysine residues increased in the order methyl linoleate < methyl linolenate < methyl arachidonate. The amounts of alkyl hydroperoxides, malondialdehyde, and a number of other aldehydes that accumulated when polyunsaturated fatty acids were oxidized in the presence of BSA were significantly lower than that observed in the absence of BSA. Direct treatment of proteins with various lipid hydroperoxides led to a slight increase in the formation of protein carbonyl derivatives, whereas treatment with the hydroperoxides together with Fe(II) led to a substantial increase in the formation of protein carbonyls. These results are consistent with the proposition that metal-catalyzed oxidation of polyunsaturated fatty acids can contribute to the generation of protein carbonyls by direct interaction of lipid oxidation products (␣,␤-unsaturated aldehydes) with lysine residues (Michael addition reactions) and also by interactions with alkoxyl radicals obtained by Fe(II) cleavage of lipid hydroperoxides that are formed. In addition, saturated aldehydes derived from the polyunsaturated fatty acids likely react with lysine residues to form Schiff base adducts.

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Mechanism of reaction of myoglobin with the lipid hydroperoxide hydroperoxyoctadecadienoic acid

Cited by 72 publications

References 33 publications

On the Role of Molecular Oxygen in Lipoxygenase Activation

On the Role of Molecular Oxygen in Lipoxygenase Activation

Engineering Tyrosine-Based Electron Flow Pathways in Proteins: The Case of Aplysia Myoglobin

Modifications of proteins by polyunsaturated fatty acid peroxidation products

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