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Enzyme
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Target Concepts:
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Query: EC:1.3.99.3 (
acyl-CoA dehydrogenase
)
1,425
document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)
The oxidation of palmitoyl- and octanoylcarnitine in liver mitochondria from normal and clofibrate-treated male rats was studied by measuring the ADP-stimulated oxygen consumption and acetyl group production (the sum of formed ketone bodies, acetylcarnitine and citrate). In the absence of malate the treatment approximately doubled the rate of acylcarnitine oxidation. In normal mitochondria the acetyl groups consisted almost totally of ketone bodies. The clofibrate-induced increase in acetyl group production was attributable to enhanced rates of ketone body and acetylcarnitine formation. The observed increase in acylcarnitine oxidation was associated with an elevated beta-hydroxybutyrate: acetoacetate ratio, reflecting an increased mitochondrial NADH:NAD+ ratio. In normal mitochondria the addition of malate in the presence of fluorocitrate doubled the rate of beta oxidation by forming citrate. The beta oxidation in mitochondria from clofibrate-treated rats was virtually unresponsive to added malate. The clofibrate-induced increase in ketogenesis was confirmed in disintegrated mitochondria. The treatment approximately doubled the rate of ketone body production from acetyl-CoA in disrupted organelles. The enhanced capacity of ketogenesis was accompanied by increased activity of the specific
acetoacetyl-CoA thiolase
(EC 2.3.1.8), which is the first step enzyme of the pathway. Clofibrate administration also increased the activities of general oxoacyl-CoA thiolase (EC 2.3.1.16), palmitoyl-CoA dehydrogenase (
EC 1.3.99.3
), and butyryl-CoA dehydrogenase (EC 1.3.99.2), which all take part in the beta oxidation of fatty acids.
...
PMID:Effect of clofibrate treatment on acylcarnitine oxidation in isolated rat liver mitochondria. 3 20
Rat liver 3-ketoacyl-CoA thiolase, a mitochondrial matrix enzyme which catalyzes a step of fatty acid beta-oxidation, was synthesized in a rabbit reticulocyte lysate cell-free system. The in vitro product was apparently the same in molecular size and charge as the subunit of the mature enzyme. The enzyme synthesized in vitro was transported into isolated rat liver mitochondria in an energy-dependent manner. In pulse experiments with isolated rat hepatocytes at 37 degrees C, the radioactivity of the newly synthesized enzyme in the cytosolic fraction remained essentially unchanged during 5-20 min of incubation, whereas that of the enzyme in the particulate fraction increased with time during the incubation. The pulse-labeled enzyme disappeared with an apparent half-life of less than 3 min from the cytosolic fraction, in pulse-chase experiments. Purified 3-ketoacyl-CoA thiolase inhibited the mitochondrial uptake and processing of the precursors of the other matrix enzymes, ornithine carbamoyltransferase,
medium-chain acyl-CoA dehydrogenase
and
acetoacetyl-CoA thiolase
. These results indicate that 3-ketoacyl-CoA thiolase has an internal signal which is recognized by the mitochondria and suggest that this enzyme and the three others are transported into the mitochondria by a common pathway.
...
PMID:Transport of proteins into mitochondrial matrix. Evidence suggesting a common pathway for 3-ketoacyl-CoA thiolase and enzymes having presequences. 285 88
The metabolism of 3-mercaptopropionic acid in mitochondria was studied by use of purified mitochondrial enzymes and rat heart mitochondria. Metabolites of 3-mercaptopropionic acid were separated by high performance liquid chromatography and identified by comparing them with chemically synthesized derivatives of 3-mercaptopropionic acid. The initial step in the metabolism of 3-mercaptopropionic acid is its conversion to a CoA thioester, most likely catalyzed by medium-chain acyl-CoA synthetase. The resulting 3-mercaptopropionyl-CoA is a poor substrate of
acyl-CoA dehydrogenase
but substitutes effectively for CoASH in reactions catalyzed by 3-ketoacyl-CoA thiolase and
acetoacetyl-CoA thiolase
. S-Acyl-3-mercaptopropionyl-CoA thioesters formed in the thiolase-catalyzed reactions are not at all or only poorly acted upon by acyl-CoA dehydrogenases. However, they are hydrolyzed by thioesterase(s) to CoASH and S-acyl-3-mercaptopropionic acid. The hydrolysis of S-acyl-3-mercaptopropionyl-CoA thioesters proceeds more rapidly than the hydrolysis of fatty acyl-CoA thioesters of comparable chain lengths. Free CoASH is also regenerated from S-acetyl-3-mercaptopropionyl-CoA and more rapidly from 3-mercaptopropionyl-CoA as a result of their reactions with carnitine catalyzed by carnitine acetyltransferase. These findings lead to the suggestion that the major mitochondrial CoA-containing metabolites of 3-mercaptopropionic acid are S-acyl-3-mercaptopropionyl-CoA thioesters.
...
PMID:Mitochondrial metabolism of 3-mercaptopropionic acid. Chemical synthesis of 3-mercaptopropionyl coenzyme A and some of its S-acyl derivatives. 399 72
The biogenesis of seven enzymes involved in the mitochondrial fatty acid beta-oxidation of rat liver was studied. Hepatic RNA was translated in vitro in a rabbit reticulocyte lysate cell-free system and the translation products were immunoprecipitated, subjected to sodium dodecyl sulfate-polyacrylamide gel electrophoresis and visualized by fluorography. The translation products obtained in vitro of medium-chain and/or
long-chain acyl-CoA dehydrogenase
(these enzymes were immunochemically cross-reactive), enoyl-CoA hydratase, 3-hydroxyacyl-CoA dehydrogenase, and
acetoacetyl-CoA thiolase
and probably also short-chain acyl-CoA dehydrogenase were larger than the subunits of the corresponding mature enzymes by 2-4.5 kDa, whereas the 3-oxoacyl-CoA thiolase obtained in vitro was approximately the same size as the mature subunit. The free polysome fraction of rat liver was 4.3-9.0-times more active than the membrane-bound polysome fraction in the synthesis of these seven enzymes. The enzyme activities were increased after administration of di(2-ethylhexyl)phthalate; the extent of the increase varied from one enzyme to another. The increase in the cell-free translation activity of total hepatic RNA for these enzymes after administration of the chemical was markedly different among individual enzymes and higher than that in the rates of synthesis of the corresponding enzymes which were determined by the experiment in vivo.
...
PMID:Biosynthesis of enzymes of rat-liver mitochondrial beta-oxidation. 648 37
The delay in ovarian maturation in farmed black tiger shrimp Penaeus monodon has resulted in the widespread practice of feeding broodstock with the polychaete Perinereis nuntia and their unilateral eyestalk ablation. Although this practice alters fatty acid content in shrimp ovaries and hepatopancreas, its effects on fatty acid regulatory genes are yet to be systematically examined. Here, microarray analysis was performed on hepatopancreas and ovary cDNA collected from P. monodon at different ovarian maturation stages, revealing that 72 and 58 genes in fatty acid regulatory pathways were differentially expressed in hepatopancreas and ovaries respectively. Quantitative real-time PCR analysis revealed that ovarian maturation was associated with higher expression levels of
acetyl-CoA acetyltransferase
,
acyl-CoA dehydrogenase
, acyl-CoA oxidase 3 and long-chain fatty acid transport protein 4 in hepatopancreas, whereas the expression levels of 15 fatty acid regulatory genes were increased in shrimp ovaries. To distinguish the effects of different treatments, transcriptional changes were examined in P. monodon with stage 1 ovaries before polychaete feeding, after 1 month of polychaete feeding and after eyestalk ablation. Polychaete feeding resulted in lower expression levels of enoyl-CoA hydratase and acyl-CoA synthetase medium-chain family member 4, while the expression level of phosphatidylinositide phosphatase SAC1 was higher in shrimp hepatopancreas and ovaries. Additionally, eyestalk ablation resulted in a higher expression level of long-chain fatty acid-CoA ligase 4 in both tissues. Together, our findings describe the dynamics of fatty acid regulatory pathways during crustacean ovarian development and provide potential target genes for alternatives to eyestalk ablation in the future.
...
PMID:Dynamics of fatty acid regulatory genes during ovarian development in Penaeus monodon. 3032 47