scholarly journals Comparison of metabolic fluxes of cis-5-enoyl-CoA and saturated acyl-CoA through the β-oxidation pathway

1995 ◽  
Vol 307 (1) ◽  
pp. 23-28 ◽  
Author(s):  
K Y Tserng ◽  
L S Chen ◽  
S J Jin
Keyword(s):  
Stable Isotope ◽  
Rat Liver ◽  
Chromatographic Method ◽  
Spectrophotometric Assay ◽  
Beta Oxidation ◽  
Metabolic Fluxes ◽  
Hydroxyacyl Coa Dehydrogenase ◽  
Acyl Coa Oxidase ◽  
Acyl Coa Dehydrogenases ◽  
Gas Chromatographic Method

The metabolic fluxes of cis-5-enoyl-CoAs through the beta-oxidation cycle were studied in solubilized rat liver mitochondrial samples and compared with saturated acyl-CoAs of equal chain length. These studies were accomplished using either spectrophotometric assay of enzyme activities and/or the analysis of metabolites and precursors using a gas chromatographic method after conversion of CoA esters into their free acids. Cis-5-enoyl-CoAs were dehydrogenated by acyl-CoA oxidase or acyl-CoA dehydrogenases at significantly lower rates (10-44%) than saturated acyl-CoAs. However, enoyl-CoA hydratase hydrated trans-2-cis-5-enoyl-CoA at a faster rate (at least 1.5-fold) than trans-2-enoyl-CoA. The combined activities of 3-hydroxyacyl-CoA dehydrogenase and 3-ketoacyl-CoA thiolase for 3-hydroxy-cis-5-enoyl-CoAs derived from cis-5-enoyl-CoAs were less than 40% of the activity for the corresponding 3-hydroxyacyl-CoAs prepared from saturated acyl-CoAs. Rat liver mitochondrial beta-oxidation enzymes were capable of metabolizing cis-5-enoyl-CoA via one cycle of beta-oxidation to cis-3-enoyl-CoA with two less carbons. However, the overall rates of one cycle of beta-oxidation, as determined with stable-isotope-labelled tracer, was only 15-25%, for cis-5-enoyl-CoA, of that for saturated acyl-CoA. In the presence of NADPH, the metabolism of cis-5-enoyl-CoAs was switched to the reduction pathway.(ABSTRACT TRUNCATED AT 250 WORDS)

scholarly journals Acyl-Coa oxidase and hydratase-dehydrogenase, two enzymes of the peroxisomal beta-oxidation system, are synthesized on free polysomes of clofibrate-treated rat liver.

1984 ◽  
Vol 99 (6) ◽  
pp. 2241-2246 ◽  
Author(s):  
R A Rachubinski ◽  
Y Fujiki ◽  
R M Mortensen ◽  
P B Lazarow
Keyword(s):  
Rat Liver ◽  
Translational Efficiency ◽  
Beta Oxidation ◽  
Sds Page ◽  
Reticulocyte Lysate ◽  
Normal Rat ◽  
Membrane Bound ◽  
Hydroxyacyl Coa Dehydrogenase ◽  
Acyl Coa Oxidase ◽  
Oxidation System

We investigated the site of synthesis of two abundant proteins in clofibrate-induced rat hepatic peroxisomes. RNA was extracted from free and membrane-bound polysomes, heated to improve translational efficiency, and translated in the mRNA-dependent, reticulocyte-lysate-cell-free, protein-synthesizing system. The peroxisomal acyl-CoA oxidase and enoyl-CoA hydratase-beta-hydroxyacyl-CoA dehydrogenase 35S-translation products were isolated immunochemically, analyzed by SDS PAGE and fluorography, and quantitated by densitometric scanning. The RNAs coding for these two peroxisomal proteins were found predominantly on free polysomes, and the translation products co-migrated with the mature proteins. As in normal rat liver, preproalbumin and catalase were synthesized mainly by membrane-bound and by free polysomes, respectively. mRNAs for a number of minor 35S-translation products also retained by the anti-peroxisomal immunoadsorbent were similarly found on free polysomes. These results, together with previous data, allow the generalization that the content proteins of rat liver peroxisomes are synthesized on free polysomes, and the data imply a posttranslational packaging mechanism for these major content proteins.

scholarly journals Acyl-CoA synthetase and the peroxisomal enzymes of β-oxidation in human liver. Quantitative analysis of their subcellular localization

1984 ◽  
Vol 224 (3) ◽  
pp. 709-720 ◽  
Author(s):  
M Bronfman ◽  
N C Inestrosa ◽  
F O Nervi ◽  
F Leighton
Keyword(s):  
Human Liver ◽  
Fatty Acyl ◽  
Single Step ◽  
Synthetase Activity ◽  
Beta Oxidation ◽  
Analysis Of Results ◽  
Fractionation Method ◽  
Hydroxyacyl Coa Dehydrogenase ◽  
Acyl Coa Oxidase ◽  
Rate Limiting

The presence of acyl-CoA synthetase (EC 6.2.1.3) in peroxisomes and the subcellular distribution of beta-oxidation enzymes in human liver were investigated by using a single-step fractionation method of whole liver homogenates in metrizamide continuous density gradients and a novel procedure of computer analysis of results. Peroxisomes were found to contain 16% of the liver palmitoyl-CoA synthetase activity, and 21% and 60% of the enzyme activity was localized in mitochondria and microsomal fractions respectively. Fatty acyl-CoA oxidase was localized exclusively in peroxisomes, confirming previous results. Human liver peroxisomes were found to contribute 13%, 17% and 11% of the liver activities of crotonase, beta-hydroxyacyl-CoA dehydrogenase and thiolase respectively. The absolute activities found in peroxisomes for the enzymes investigated suggest that in human liver fatty acyl-CoA oxidase is the rate-limiting enzyme of the peroxisomal beta-oxidation pathway, when palmitic acid is the substrate.

scholarly journals Participation of peroxisomes in lipid biosynthesis in the harderian gland of guinea pig

1989 ◽  
Vol 262 (2) ◽  
pp. 677-680 ◽  
Author(s):  
S Horie ◽  
T Suga
Keyword(s):  
Guinea Pig ◽  
Rat Liver ◽  
Harderian Gland ◽  
Dihydroxyacetone Phosphate ◽  
Glycerol Ether ◽  
Beta Oxidation ◽  
Ether Phospholipid ◽  
Peroxisomal Enzyme ◽  
Acyl Coa Oxidase ◽  
Oxidation System

Peroxisomal enzyme activities in the guinea-pig harderian gland, which has a unique lipid composition, were studied. Activities of catalase, acyl-CoA oxidase and the cyanide-insensitive acyl-CoA beta-oxidation system in this tissue were comparable with those in rat liver. The activities of dihydroxyacetone phosphate acyltransferase (DHAPAT, EC 2.3.1.42) and alkyl-DHAP synthase (EC 2.5.1.26) were appreciable, and the distributions of both activities were consistent with that of sedimentable catalase activity. Glycerol-3-phosphate acyltransferase (GPAT, EC 2.3.1.15), which is localized in both microsomes (microsomal fractions) and mitochondria in the rat liver, was a peroxisomal enzyme in the harderian gland, though the activity was only about one-tenth of the DHAPAT activity. These enzymes had different pH profiles and substrate specificity. The existence of high activities of enzymes of the acyl-DHAP pathway in peroxisomes suggests the physiological significance of peroxisomes in the biosynthesis of glycerol ether phospholipid and 1-alkyl-2,3-diacylglycerol in the guinea-pig harderian gland.

Analysis of transcripts homologous to acyl-CoA oxidase and enoyl-CoA hydratase 3-hydroxyacyl-CoA dehydrogenase induced in rat liver by methylclofenapate

1987 ◽  
Vol 37 (1) ◽  
pp. 115-121 ◽  
Author(s):  
S. McQuaid ◽  
S.E.H. Russell ◽  
S.A. Withe ◽  
C.M. Fearson ◽  
C.R. Elcombe ◽  
...  
Keyword(s):  
Rat Liver ◽  
Hydroxyacyl Coa Dehydrogenase ◽  
Acyl Coa Oxidase ◽  
Enoyl Coa Hydratase

scholarly journals Effects of tetradecylthiopropionic acid and tetradecylthioacrylic acid on rat liver lipid metabolism

1995 ◽  
Vol 305 (2) ◽  
pp. 591-597 ◽  
Author(s):  
S Skrede ◽  
P Wu ◽  
H Osmundsen
Keyword(s):  
Lipid Metabolism ◽  
Rat Liver ◽  
Liver Lipid ◽  
Isolated Hepatocytes ◽  
Liver Mitochondria ◽  
Carnitine Palmitoyltransferase ◽  
Rat Liver Mitochondria ◽  
Beta Oxidation ◽  
Liver Lipid Metabolism ◽  
Acyl Coa Oxidase

Studies of effects of 4-thia-substituted fatty acid analogues on rat liver lipid metabolism are described. With isolated hepatocytes tetradecylthiopropionate was shown to divert [1-14C]oleate from beta-oxidation into esterification, the total amount of [1-14C]oleate metabolized remaining unchanged. Tetradecylthiopropionyl-CoA was a good substrate for mitochondrial carnitine palmitoyltransferases I and II (EC 2.3.1.21), acyl-CoA oxidase (EC 1.3.3.6), for the microsomal (but not mitochondrial) glycerophosphate acyltransferase (EC 2.3.1.15), and for long-chain acyl-CoA dehydrogenase (EC 1.3.99.3). In isolated hepatocytes, its 4-thia-trans-2-enoic derivative, tetradecylthioacrylate, inhibits both beta-oxidation of, and incorporation of, [1-14C]oleate into lipids. In rat liver mitochondria tetradecylthiocrylate inhibited beta-oxidation. The degree of inhibition was not markedly increased by preincubation with tetradecylthioacrylate. Tetradecylthioacrylyl-CoA was a poor substrate for carnitine palmitoyltransferase I, and inhibited carnitine palmitoyltransferase II, microsomal glycerophosphate acyltransferase and acyl-CoA oxidase. It is concluded that the inhibitory effects of tetradecylthiopropionyl-CoA are expressed intramitochondrially, whereas primary sites of inhibition by tetradecylthioacrylyl-CoA are extramitochondrial.

scholarly journals Peroxisomal and mitochondrial beta-oxidation in the rat kidney: distribution of fatty acyl-coenzyme A oxidase and 3-hydroxyacyl-coenzyme A dehydrogenase activities along the nephron.

1982 ◽  
Vol 30 (5) ◽  
pp. 441-444 ◽  
Author(s):  
M Le Hir ◽  
U C Dubach
Keyword(s):  
Proximal Tubule ◽  
Coenzyme A ◽  
Rat Kidney ◽  
Mitochondrial Pathway ◽  
Fatty Acyl ◽  
Beta Oxidation ◽  
Collecting Ducts ◽  
Hydroxyacyl Coa Dehydrogenase ◽  
Acyl Coa Oxidase ◽  
Acyl Coenzyme A

In order to determine the localization of the peroxisomal and the mitochondrial pathways of beta-oxidation in the rat kidney, fatty acyl-coenzyme A (CoA) oxidase and 3-hydroxyacyl-CoA dehydrogenase activities were measured in glomeruli and in eight proximal and distal segments of the nephron. Structurally defined segments were dissected and analyzed with microchemical assays. The peroxisomal fatty acyl-CoA oxidase is restricted to the proximal tubule. The 3-hydroxyacyl-CoA dehydrogenase activity represents mainly the mitochondrial pathway and is similarly distributed in all cortical proximal and distal segments. It is much lower in glomeruli and collecting ducts. The distribution patterns of the two enzymes remain the same after 48 hr of starvation, although the activity of fatty acyl-CoA oxidase increases in glomeruli, proximal convolution, and collecting ducts. It is concluded that the capacity for mitochondrial beta-oxidation of fatty acids is similar in the proximal and the distal nephron. The proximal tubule possesses, additionally, a peroxisomal pathway for beta-oxidation with a capacity of the same order of magnitude as in liver cells.

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