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.

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.

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.

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