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.

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 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 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 Investigation of peroxisomal lipid beta-oxidation enzymes in guinea pig liver peroxisomes by immunoblotting and immunocytochemistry.

1992 ◽  
Vol 40 (12) ◽  
pp. 1909-1918 ◽  
Author(s):  
K Yamamoto ◽  
A Völkl ◽  
H D Fahimi
Keyword(s):  
Guinea Pig ◽  
Light And Electron Microscopy ◽  
Molecular Size ◽  
Acid Oxidase ◽  
Beta Oxidation ◽  
Homologous Proteins ◽  
Pig Liver ◽  
The Matrix ◽  
Acyl Coa Oxidase ◽  
Guinea Pig Liver

We investigated the immunoreactivity of the peroxisomal lipid beta-oxidation enzymes acyl-CoA oxidase, trifunctional protein, and thiolase in guinea pig liver and compared it with that of homologous proteins in rat, using immunoblotting of highly purified peroxisomal fractions and monospecific antibodies to rat proteins. In addition, the immunocytochemical localization of beta-oxidation enzymes in guinea pig liver was compared with that of catalase. All antibodies showed crossreactivity between the two species, indicating that these peroxisomal proteins have been well conserved, although all exhibited some differences with respect to molecular size and, in the case of acyl-CoA oxidase, in frequency of the immunoreactive bands. In the latter case, a distinct second band in the 70 KD range was observed in guinea pig, in addition to the regular band due to subunit A present in rat liver. This novel band could be due either to trihydroxycoprostanoyl-CoA oxidase or to the non-inducible branched chain fatty acid oxidase described recently. All three beta-oxidation enzymes were immunolocalized by light and electron microscopy to the matrix of peroxisomes, in contrast to catalase, which is also found in the cytoplasm and the nucleus of hepatocytes in guinea pig liver.

Hepatic uptake of intact glutathione S-conjugate, inhibition by organic anions, and sinusoidal catabolism

1993 ◽  
Vol 265 (3) ◽  
pp. G547-G554
Author(s):  
C. A. Hinchman ◽  
A. T. Truong ◽  
N. Ballatori
Keyword(s):  
Guinea Pig ◽  
Rat Liver ◽  
Marked Decrease ◽  
Hepatic Uptake ◽  
Half Time ◽  
High Concentrations ◽  
Rat Livers ◽  
Dose Dependent ◽  
Uptake And Metabolism ◽  
Guinea Pig Liver

To identify potential mechanisms for hepatic removal of circulating glutathione (GSH) conjugates, uptake and metabolism of S-2,4-dinitrophenylglutathione (DNP-SG) were examined in isolated perfused livers from rat and guinea pig. Guinea pig livers perfused with 5 mumol of DNP-SG in a recirculating system (50 microM initial concn) rapidly cleared the conjugate from the perfusate (half time 3.7 min), whereas clearance was considerably slower in rat liver (half time 35 min). Disappearance of DNP-SG from the perfusate was accompanied by a simultaneous appearance of DNP-SG and its metabolites in bile. Addition of acivicin, an inhibitor of gamma-glutamyltransferase (gamma-GT), to the perfusate resulted in a marked decrease in DNP-SG clearance by guinea pig liver but had no effect in rat liver, suggesting that in the guinea pig this process is largely dependent on sinusoidal gamma-GT activity. However, even in the presence of acivicin, rat and guinea pig livers removed nearly one-half of the administered DNP-SG from the recirculating perfusate over 30 min. High concentrations of DNP-SG were found in bile (up to 3.7 mM), indicating that the liver is capable of transporting the intact conjugate from the circulation. When rat livers were perfused with higher concentrations of DNP-SG (100 and 250 microM), biliary excretion of DNP-SG increased dose dependently, with concentrations in bile reaching 10 mM at the higher dose. This was accompanied by a dose-dependent choleresis.(ABSTRACT TRUNCATED AT 250 WORDS)

scholarly journals Peroxisomal beta-oxidation. Purification of four novel 3-hydroxyacyl-CoA dehydrogenases from rat liver peroxisomes.

1994 ◽  
Vol 269 (43) ◽  
pp. 27125-27135
Author(s):  
D K Novikov ◽  
G F Vanhove ◽  
H Carchon ◽  
S Asselberghs ◽  
H J Eyssen ◽  
...  
Keyword(s):  
Rat Liver ◽  
Beta Oxidation ◽  
Liver Peroxisomes
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