Beta-oxidation of elaidic acid and delta 3, delta 2-enoyl-CoA isomerases in the rat.
Item
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Title
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Beta-oxidation of elaidic acid and delta 3, delta 2-enoyl-CoA isomerases in the rat.
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Identifier
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AAI3144155
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identifier
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3144155
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Creator
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Yu, Wenfeng.
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Contributor
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Adviser: Horst Schulz
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Date
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2004
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Language
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English
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Publisher
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City University of New York.
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Subject
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Chemistry, Biochemistry
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Abstract
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The degradation of elaidic acid, oleic acid, and stearic acid by rat mitochondria was studied to determine if the presence of a trans double bond in place of a cis double bond or no double bond affects beta-oxidation. Rat mitochondria from liver or heart effectively degraded the coenzyme A derivatives of all three fatty acids. However, with elaidoyl-CoA as substrate, a major metabolite accumulated in the mitochondrial matrix. This metabolite was isolated and identified as 5-trans-tetradecenoyl-CoA. In contrast, little or none of the corresponding metabolites were detected with oleoyl-CoA or stearoyl-CoA as substrates. A kinetic study of long-chain acyl-CoA dehydrogenase (LCAD) and very long-chain acyl-CoA dehydrogenase (VLCAD) revealed that 5-trans-tetradecenoyl-CoA is a poorer substrate of LCAD than is 5-cis-tetradecenoyl-CoA, while both unsaturated acyl-CoAs are poor substrates of VLCAD when compared to myristoyl-CoA. Tetradecenoic acid and tetradecenoylcarnitine were detected by gas chromatography/mass spectrometry and tandem mass spectrometry, respectively, when rat liver mitochondria were incubated with elaidoyl-CoA but not when oleoyl-CoA was the substrate. These observations support the conclusion that 5-trans-tetradecenoyl-CoA accumulates in the mitochondrial matrix because it is less efficiently dehydrogenated by LCAD than its cis isomer and that the accumulation of this beta-oxidation intermediate facilitates its hydrolysis and conversion to 5-trans-tetradecenoylcamitine thereby permitting a partially degraded fatty acid to escape from mitochondria.;The degradation of unsaturated fatty acids by beta-oxidation involves Delta 3, Delta2-enoyl-CoA isomerases (enoyl-CoA isomerases) that catalyze 3-cis → 2-trans and 3- trans → 2-trans isomerizations of enoyl-CoAs and the 2,5 → 3,5 isomerization of dienoyl-CoAs. An analysis of rat liver enoyl-CoA isomerases revealed the presence of a monofunctional enoyl-CoA isomerase (ECI) in addition to mitochondrial short-chain enoyl-CoA isomerase (mECI) in mitochondria, whereas peroxisomes contain ECI and multifunctional enzyme 1 (MFE1). Thus ECI, which previously had been described as mono-functional peroxisomal enoyl-CoA isomerase, was found to be present in both peroxisomes and mitochondria. This enzyme seems to be identical with mitochondrial long-chain enoyl-CoA isomerase. The mature form of rat liver mECI was produced by molecular cloning and heterologous expression. The crystal structure of this mECI has been solved and clearly shows that rat liver recombinant mECI is a trimer and not a dimmer as previously reported. Its general features are similar to those of other members of the hydratase/isomerase super-family.
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Type
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dissertation
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Source
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PQT Legacy CUNY.xlsx
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degree
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Ph.D.
