Rat liver metabolism of dicarboxylic acids.
Recently, we demonstrated in rat liver that dicarboxylic acids containing more than five carbons can be activated by a microsomal dicarboxylyl-CoA synthetase (J. Vamecq, E. de Hoffmann, and F. Van Hoof. Biochem. J. 230: 683-693, 1985). The products of this reaction, dicarboxylyl-CoA esters, were found to be substrates for an H2O2-generating dicarboxylyl-CoA oxidase. In the present work we report that 1) the catalytic center or the essential domains of dicarboxylyl-CoA synthetase are located at the cytosolic aspect of the endoplasmic reticulum membrane; 2) dicarboxylyl-CoA oxidase is optimally active on dodecanedioyl-CoA and is a peroxisomal enzyme; 3) cyanide-insensitive dodecanedioyl-CoA oxidation (NADH production) is catalyzed by rat liver homogenates. Cell fractionation studies disclose that, similar to dodecanedioyl-CoA oxidase (H2O2 production), the cyanide-insensitive dodecanedioyl-CoA oxidizing activity also belongs to peroxisomes; 4) a dodecanedioyl-CoA oxidoreductase reaction can be assayed by the dichlorphenolindophenol procedure in rat liver homogenates, and the activity is abundant in peroxisomal, mitochondrial, and soluble fractions; 5) by contrast with monocarboxylyl-CoA esters, the dicarboxylyl-CoAs are apparently not substrates for mitochondrial fatty acid oxidation; however, the use of dicarboxylylcarnitine esters as direct substrate for mitochondria suggests the existence of an active beta-oxidation of dicarboxylates in these organelles, which is further confirmed by experiments in which mitochondria are permeabilized with digitonin; 6) the in vivo oxidation of infused dodecanedioic acid results in a rapid appearance in urine of medium-chain dicarboxylic acids, with only 30-50% of the infused dose recovered in urine.
Vamecq
J
J
Laboratorie de Chimie Physiologique, University of Louvain, Brussels, Belgium.
Draye
J P
JP
Brison
J
J
D000214:Acyl Coenzyme A / Q000378:metabolism; D000818:Animals; D001692:Biological Transport; D002332:Carnitine O-Acetyltransferase / Q000378:metabolism; D002458:Cell Fractionation; D002463:Cell Membrane Permeability; D003066:Coenzyme A Ligases / Q000378:metabolism; D003998:Dicarboxylic Acids / Q000378:metabolism*; D004072:Digitonin / Q000494:pharmacology; D008099:Liver / Q000378:metabolism* / Q000648:ultrastructure; D008297:Male; D008830:Microbodies / Q000201:enzymology; D008862:Microsomes, Liver / Q000201:enzymology; D008930:Mitochondria, Liver / Q000201:enzymology; D010084:Oxidation-Reduction; D010088:Oxidoreductases / Q000378:metabolism; D051381:Rats; D011919:Rats, Inbred Strains; D013379:Substrate Specificity; D014018:Tissue Distribution
D000214:Acyl Coenzyme A; D003998:Dicarboxylic Acids; D010088:Oxidoreductases; C047028:dicarboxylic acid-CoA oxidase; D002332:Carnitine O-Acetyltransferase; D003066:Coenzyme A Ligases; C047027:dicarboxylic acid-CoA synthetase; D004072:Digitonin