The presence of acyl-CoA hydrolase in rat brown-adipose-tissue peroxisomes.
The subcellular distribution of acyl-CoA hydrolase was studied in rat brown adipose tissue, with special emphasis on possible peroxisomal localization. Subcellular fractionation by sucrose-density-gradient centrifugation, followed by measurement of short-chain (propionyl-CoA) acyl-CoA hydrolase in the presence of NADH, resulted in two peaks of activity in the gradient: one peak corresponded to the distribution of cytochrome oxidase (mitochondrial marker enzyme), and another peak of activity coincided with the peroxisomal marker enzyme catalase. The distribution of the NADH-inhibited short-chain hydrolase activity fully resembled that of cytochrome oxidase. The substrate-specificity curve of the peroxisomal acyl-CoA hydrolase activity indicated the presence of a single enzyme exhibiting a broad substrate specificity, with maximal activity towards fatty acids with chain lengths of 3-12 carbon atoms. The mitochondrial acyl-CoA hydrolase substrate specificity, in contrast, indicated the presence of at least two acyl-CoA hydrolases (of short- and medium-chain-length specificity). The peroxisomal acyl-CoA hydrolase activity was inhibited by CoA at low (microM) concentrations and by ATP at high concentrations (greater than 0.8 mM). In contrast with the mitochondrial short-chain hydrolase, the peroxisomal acyl-CoA hydrolase activity was not inhibited by NADH.
Alexson
S E
SE
Department of Metabolic Research, University of Stockholm, Sweden.
Osmundsen
H
H
Berge
R K
RK
D002001:Adipose Tissue, Brown / Q000201:enzymology*; D000818:Animals; D002374:Catalase / Q000378:metabolism; D002499:Centrifugation, Density Gradient; D006224:Cricetinae; D003576:Electron Transport Complex IV / Q000378:metabolism; D008647:Mesocricetus; D008830:Microbodies / Q000201:enzymology*; D008928:Mitochondria / Q000201:enzymology; D009243:NAD / Q000378:metabolism; D010170:Palmitoyl-CoA Hydrolase / Q000378:metabolism*; D051381:Rats; D011919:Rats, Inbred Strains; D013379:Substrate Specificity; D013869:Thiolester Hydrolases / Q000378:metabolism*
D009243:NAD; D002374:Catalase; D003576:Electron Transport Complex IV; D013869:Thiolester Hydrolases; D010170:Palmitoyl-CoA Hydrolase