Metabolic and enzymological studies of mitochondrial fatty acid beta oxidation.
Item
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Title
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Metabolic and enzymological studies of mitochondrial fatty acid beta oxidation.
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Identifier
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AAI9119689
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identifier
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9119689
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Creator
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Wang, Hang-yong.
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Contributor
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Adviser: Horst Schulz
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Date
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1991
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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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When 10 mM L-carnitine was added to coupled rat heart mitochondria at state 4 respiration, the rate of palmitoylcarnitine {dollar}\beta{dollar}-oxidation increased more than 4-fold, while the same addition had little effect on {dollar}\beta{dollar}-oxidation at state 3 respiration. Rates of respiration were unaffected by the addition of carnitine. Neither oxaloacetate nor acetoacetate, added to mitochondria to lower the intramitochondrial NADH/NAD{dollar}\sp+{dollar} ratio, stimulated {dollar}\beta{dollar}-oxidation. Determination of the intramitochondrial ratio of acetyl-CoA/CoASH by high performance liquid chromatography yielded a value close to 10 for state 4 respiration as compared to 2.5 at state 3 respiration. Addition of 10 mM carnitine caused a dramatic decrease of this ratio to less than 0.2 at both respiration states. All data agree with the hypothesis that in heart mitochondria the rate of {dollar}\beta{dollar}-oxidation is controlled by the acetyl-CoA/CoASH ratio via the regulation of 3-ketoacyl-CoA thiolase (EC 2.3.1.16).;A long-chain L-3-hydroxyacyl-CoA dehydrogenase (HDH) was solubilized from pig heart mitochondrial membranes with Triton X-100 and separated from the soluble general HDH (EC 1.1.1.35) by gel filtration in the presence of 0.1 M EDTA and 2.5 M KCl. Gradient gel electrophoresis of native proteins followed by activity staining with substrates showed that the detergent-solubilized long-chain HDH activity behaved like a high molecular protein similar to its behavior on a gel filtration column. In contrast to the almost complete immunoprecipitation of general HDH, the long-chain HDH activity could not be precipitated with antibodies raised against general HDH. Furthermore, the long-chain activity in mitochondrial extracts solubilized with 1% octyl glucoside could be separated from general HDH activity by antibody affinity chromatography. On the other hand, preliminary results using Western blotting suggested that the long-chain HDH activity could be recognized by anti-general HDH antibodies.;The mitochondrial {dollar}\beta{dollar}-oxidation of all trans-octa-2,4,6-trienoic acid was studied with the aim of elucidating the degradation of unsaturated fatty acids with conjugated double bonds. It is concluded that polyunsaturated fatty acids with two conjugated double bonds extending from even-numbered carbon atoms can be completely degraded via {dollar}\beta{dollar}-oxidation because their presumed 2,4,6-trienoyl-CoA intermediates are substrates of 2,4-dienoyl-CoA reductase. (Abstract shortened with permission of author.).
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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.
