Acetate generation in rat liver mitochondria; acetyl-CoA hydrolase activity is demonstrated by 3-ketoacyl-CoA thiolase

• Published in: Biochimica et biophysica acta Vol. 1761; no. 1; pp. 17 - 23
• Main Authors: Yamashita, Hiromi, Itsuki, Ai, Kimoto, Masumi, Hiemori, Miki, Tsuji, Hideaki
• Format: Journal Article
• Language: English
• Published: Netherlands Elsevier B.V 2006
• Subjects: 3-ketoacyl-CoA thiolase; Acetate metabolism; Acetates - metabolism; Acetyl-CoA C-Acyltransferase - metabolism; Acetyl-CoA hydrolase; Acetyl-CoA Hydrolase - isolation & purification; Acetyl-CoA Hydrolase - metabolism; Acyl Coenzyme A - metabolism; Animals; Chromatography, Gel; Diethylhexyl Phthalate - pharmacology; Enzyme Activation; Kinetics; Male; Mitochondria, Liver - drug effects; Mitochondria, Liver - enzymology; Mitochondria, Liver - metabolism; Peroxisome proliferator; Rat liver mitochondria; Rats; Rats, Sprague-Dawley; β-oxidation of fatty acid; DTNB; 3-ketoacyl-CoA thiolase (EC 2.3.1.16); 3-ketoacyl-CoA thiolase; PAGE; Rat liver mitochondria; Enzymes: acetyl-CoA hydrolase (EC 3.1.2.1); Peroxisome proliferator; Acetyl-CoA hydrolase; BSA; CoA; Acetate metabolism; DEHP; β-oxidation of fatty acid
• ISSN: 1388-1981; 0006-3002; 1879-2618
• DOI: 10.1016/j.bbalip.2006.01.001

Acetate has been found as an endogenous metabolite of β-oxidation of fatty acids in liver. In order to investigate the regulation of acetate generation in liver mitochondria, we attempted to purify a mitochondrial acetyl-CoA hydrolase in rat liver. This acetyl-CoA-hydrolyzing activity in isolated mitochondria was induced by the treatment of rats with di(2-ehtylhexyl)phthalate (DEHP), a peroxisome proliferator which induces expression of several peroxisomal and mitochondrial enzymes involved in β-oxidation of fatty acids. The purified enzyme was 43-kDa in molecular mass by SDS/PAGE. Internal amino acid sequencing of this enzyme revealed that it was identical with mitochondrial 3-ketoacyl-CoA thiolase, suggesting that this enzyme has two kinds of activities, 3-ketoacyl-CoA thiolase and acetyl-CoA hydrolase activities. Kinetic studies clearly indicated that this enzyme had the both activities and each activity was inhibited by the substrates of the other activity, that is, 3-ketoacyl-CoA thiolase activity was inhibited by acetyl-CoA, on the other hand, acetyl-CoA hydrolase activity was inhibited by acetoacetyl-CoA in a competitive manner. These findings suggested that acetate generation in liver mitochondria is a side reaction of this known enzyme, 3-ketoacyl-CoA thiolase, and this enzyme may regulate its activities depending on each substrate level.