Biosynthesis of phosphatidic acid by glycerophosphate acyltransferases in rat liver mitochondria and microsomes

1990 ◽  
Vol 68 (12) ◽  
pp. 1380-1392 ◽  
Author(s):  
Amy Y. P. Mok ◽  
William C. McMurray
Keyword(s):  
Phosphatidic Acid ◽  
Rat Liver ◽  
Neutral Lipids ◽  
Divalent Cations ◽  
Liver Mitochondria ◽  
Fatty Acyl ◽  
Subcellular Fractions ◽  
Rat Liver Mitochondria ◽  
Acyl Donor ◽  
Palmitoyl Carnitine

The acyltransferases that catalyze the synthesis of phosphatidic acid from labelled sn-[14C]glycero-3-phosphate and fatty acyl carnitine or coenzyme A derivatives have been shown to be present in both isolated mitochondria and microsomes from rat liver. The major reaction product was phosphatidic acid in both subcellular fractions. A small quantity of lysophosphatidic acid and neutral lipids were produced as by-products. Divalent cations had significant effects on both mitochondrial and microsomal fractions in stimulating acylation using palmitoyl CoA, but not when palmitoyl carnitine was used as the acyl donor. Palmitoyl CoA and palmitoyl carnitine could be used for acylation by both mitochondria and microsomes. Mitochondria were more permeable to palmitoyl carnitine and readily used it as the substrate for acylation. On the other hand, microsomes yielded a better rate with palmitoyl CoA and the rate of acylation from palmitoyl carnitine in microsomes was correlated with the degree of mitochondrial contamination. The enzymes were partially purified from Triton X-100 extracts of subcellular fractions. Based on the differences of substrate utilization, products formed, divalent cation effects, molecular weights, and polarity, the mitochondrial and microsomal acyltransferases appeared to be different enzymes.Key words: glycerophosphate, acyltransferase, mitochondria, microsomes, phosphatidic acid.

Comparative studies of CDP-diacylglycerol synthase in rat liver mitochondria and microsomes

1993 ◽  
Vol 71 (3-4) ◽  
pp. 183-189 ◽  
Author(s):  
Amy Y. P. Mok ◽  
Gordon E. McDougall ◽  
William C. McMurray
Keyword(s):  
Phosphatidic Acid ◽  
Rat Liver ◽  
Mitochondrial Fraction ◽  
Liver Mitochondria ◽  
Subcellular Fractions ◽  
Rat Liver Mitochondria ◽  
Mitochondrial Enzyme ◽  
Egg Lecithin ◽  
Microsomal Membranes ◽  
Concentration Curves

CDP-diacylglycerol for polyglycerophosphatide biogenesis can be synthesized within rat liver mitochondria. Contamination by microsomal membranes cannot account for the CDP-diacylglycerol synthesis found in the mitochondria. Phosphatidic acid from egg lecithin was the best substrate for the synthesis of CDP-diacylglycerol in both subcellular fractions. Concentration curves for CTP and Mg2+ differed for the two subcellular fractions. Microsomal CDP-diacylglycerol synthase was specifically stimulated by the nucleotide GTP; this stimulatory effect by GTP was not observed in the mitochondrial fraction. By comparison, the microsomal enzyme was more sensitive towards sulfhydryl inhibitors than the mitochondrial enzyme. The enzymes could be solubilized from the membrane fractions using 3-[(cholamidopropyl)dimethylammonio]-1-propanesulfonate, and the detergent-soluble activity could be partially restored by addition of phospholipids. Based on the differences in properties, it was concluded that there are two distinct enzyme localizations for CDP-diacylglycerol synthesis in mitochondria and microsomes from rat liver.Key words: CDP-diacylglycerol, synthase, phosphatidic acid, mitochondria, microsomes, solubilization.

Evidence for the Biosynthetic Difference between Isolated Mitochondria and Microsomes from Guinea-Pig and Rat Liver Regarding Lysophospharidic Acid, Phosphatidic Acid, CDP-Diglyceride, Phosphatidylglycerol, and Cardiolipin

1974 ◽  
Vol 52 (10) ◽  
pp. 936-939 ◽  
Author(s):  
J. B. Davidson ◽  
N. Z. Stanacev
Keyword(s):  
Guinea Pig ◽  
Phosphatidic Acid ◽  
Rat Liver ◽  
Liver Mitochondria ◽  
Rat Liver Mitochondria ◽  
Marker Enzymes ◽  
Synthetic Enzymes ◽  
Isolated Mitochondria ◽  
Significant Difference ◽  
Nadph Cytochrome C Reductase

The enzymatic activities of marker enzymes (NADPH – cytochrome c reductase and glucose-6-phosphatase) and synthetic enzymes (acyl-CoA:sn-glycero-3-phosphate acyltransferase, CTP:sn-3-phosphatidic acid cytidyltransferase, and CDP-diglyceride:sn-glycero-3-phosphate phosphatidyltransferase) were measured in both isolated mitochondria and microsomes from liver of guinea pig and rat. Results thus obtained show a significant difference in activities of these enzymes between subcellular particles within species and between two examined species. The activity of acyl-CoA:glycero-3-phosphate acyltransferase in guinea-pig mitochondria parallels the activity of microsomal marker enzymes in this fraction, while in rat liver mitochondria the activity is relatively higher and cannot be accounted for by the microsomal content as determined by marker enzymes. Implications of these results regarding mitochondrial autonomy in the biosynthesis of polyglycero-phosphatides and their precursors are discussed.

scholarly journals Inhibition in vitro of acyl-CoA dehydrogenases by 2-mercaptoacetate in rat liver mitochondria

1983 ◽  
Vol 215 (3) ◽  
pp. 457-464 ◽  
Author(s):  
F Bauché ◽  
D Sabourault ◽  
Y Giudicelli ◽  
J Nordmann ◽  
R Nordmann
Keyword(s):  
Rat Liver ◽  
Conformational Changes ◽  
Reaction Medium ◽  
Liver Mitochondria ◽  
Fatty Acyl ◽  
Rat Liver Mitochondria ◽  
Mitochondrial Matrix ◽  
Main Effect ◽  
Acyl Coa Dehydrogenases

In rat liver hypo-osmotically treated mitochondria, 2-mercaptoacetate inhibits respiration induced by palmitoyl-CoA, octanoate or butyryl-CoA only when the reaction medium is supplemented with ATP. Under this condition, NADH-stimulated respiration is not affected. In liver mitochondrial matrix, the presence of ATP is also required to observe a 2-mercaptoacetate-induced inhibition of acyl-CoA dehydrogenases tested with palmitoyl-CoA, butyryl-CoA or isovaleryl-CoA as substrate. As the oxidation of these substrates is also inhibited by the incubation medium resulting from the reaction of 2-mercaptoacetate with acetyl-CoA synthase, with conditions under which 2-mercaptoacetate has no effect, 2-mercaptoacetyl-CoA seems to be the likely inhibitory metabolite responsible for the effects of 2-mercaptoacetate. Kinetic experiments show that the main effect of the 2-mercaptoacetate-active metabolite is to decrease the affinities of fatty acyl-CoA dehydrogenases towards palmitoyl-CoA or butyryl-CoA and of isovaleryl-CoA dehydrogenase towards isovaleryl-CoA. Addition of N-ethylmaleimide to mitochondrial matrix pre-exposed to 2-mercaptoacetate results in the immediate reversion of the inhibitions of palmitoyl-CoA and isovaleryl-CoA dehydrogenations and in a delayed reversion of butyryl-CoA dehydrogenation. These results led us to conclude that (i) the ATP-dependent conversion of 2-mercaptoacetate into an inhibitory metabolite takes place in the liver mitochondrial matrix and (ii) the three fatty acyl-CoA dehydrogenases and isovaleryl-CoA dehydrogenase are mainly competitively inhibited by this compound. Finally, the present study also suggests that the inhibitory metabolite of 2-mercaptoacetate may bind non-specifically to, or induce conformational changes at, the acyl-CoA binding sites of these dehydrogenases.

scholarly journals Steady-state concentrations of coenzyme A, acetyl-coenzyme A and long-chain fatty acyl-coenzyme A in rat-liver mitochondria oxidizing palmitate

1965 ◽  
Vol 97 (2) ◽  
pp. 587-594 ◽  
Author(s):  
PB Garland ◽  
D Shepherd ◽  
DW Yates
Keyword(s):  
Rat Liver ◽  
Coenzyme A ◽  
Liver Mitochondria ◽  
Fatty Acyl ◽  
Rat Liver Mitochondria ◽  
Beta Oxidation ◽  
Acetyl Coa ◽  
Acetyl Coenzyme A ◽  
Acyl Coenzyme A ◽  
Long Chain

1. Fluorimetric assays are described for CoASH, acetyl-CoA and long-chain fatty acyl-CoA, and are sensitive to at least 50mumumoles of each. 2. Application of these assays to rat-liver mitochondria oxidizing palmitate in the absence and presence of carnitine indicated two pools of intramitochondrial CoA. One pool could be acylated by palmitate and ATP, and the other pool acylated by palmitate with ATP and carnitine, or by palmitoylcarnitine alone. 3. The intramitochondrial content of acetyl-CoA is increased by the oxidation of palmitate both in the absence and presence of l-malate. 4. The conversion of palmitoyl-CoA into acetyl-CoA by beta-oxidation takes place without detectable accumulation of acyl-CoA intermediates.

scholarly journals Inhibition by fatty acyl esters of adenine nucleotide translocation in rat-liver mitochondria

FEBS Letters ◽  
1972 ◽  
Vol 23 (3) ◽  
pp. 303-308 ◽  
Author(s):  
W.J. Vaartjes ◽  
A. Kemp ◽  
J.H.M. Souverijn ◽  
S.G. van den Bergh
Keyword(s):  
Rat Liver ◽  
Adenine Nucleotide ◽  
Liver Mitochondria ◽  
Fatty Acyl ◽  
Rat Liver Mitochondria

Different Effect Of Dgtp On 2'-Deoxyadenosine Metabolism In Mitochondria And Cytosol

1992 ◽  
Vol 47 (11-12) ◽  
pp. 893-897 ◽  
Author(s):  
Janusz Greger ◽  
Fabianowska-Majewska Krystyna
Keyword(s):  
Physical Properties ◽  
Adenosine Deaminase ◽  
Rat Liver ◽  
Liver Mitochondria ◽  
Subcellular Fractions ◽  
Rat Liver Mitochondria

Two enzymes participating in 2′-deoxyadenosine (dAdo) metabolism: dAdo kinase (dAdoK EC 2.7.1.76) and adenosine deaminase (ADA, EC 3.5.4.4) were partially purified from rat liver mitochondria and cytosol and influence of nucleosides and nucleotides on the activity of these enzymes were investigated. Mitochondrial and cytosol dAdoK are separate proteins, while ADA from both subcellular fractions possesses similar physical properties. dGTP, a com petitive inhibitor of mitochondrial dAdoK, inhibits cytosol ADA in a mixed way but activates mitochondrial ADA and cytosol dAdoK. A possible effect of dGTP on dAdo metabolism in mitochondria and cytosol is discussed

scholarly journals Phosphatidic acid biosynthesis in rat liver mitochondria and microsomal fractions. Regulation of fatty acid positional specificity

1976 ◽  
Vol 158 (2) ◽  
pp. 249-254 ◽  
Author(s):  
K S Bjerve ◽  
L N W Daae ◽  
J Bremer
Keyword(s):  
Fatty Acid ◽  
Phosphatidic Acid ◽  
Rat Liver ◽  
Microsomal Fraction ◽  
Liver Mitochondria ◽  
Rat Liver Mitochondria ◽  
Acid Biosynthesis ◽  
Positional Specificity ◽  
Fatty Acid Specificity ◽  
High Concentrations

The positional and fatty acid specificity of phosphatidic acid biosynthesis in rat liver mitochondria and microsomal fractions was studied by using acylcarnitines, CoA and an excess of carnitine palmitoyltransferase (EC 2.3.1.21) as the source of acyl-CoA. In the mitochondria, the preference for palmitic acid at the 1-position is increased at high acyl-CoA concentrations, whereas it is decreased in the microsomal fraction. There was no change in the fatty acid specificity at the 2-position with different acyl-CoA concentrations in any of the factions. The preference in mitochondria for linoleic acid at the 2-position is strongly increased at high concentrations of lysophosphatidic acid.

Sign in / Sign up

Export Citation Format

Share Document