title: Modulation of branched-chain 2-oxoacid dehydrogenase activity by adenine nucleotides in isolated rat liver mitochondria.
abstract: Feeding a 17.5% amino acid diet to rats results in inactivation of the hepatic branched-chain 2-oxoacid dehydrogenase complex. Reactivation occurs when preincubating mitochondria in the presence of 0.3 mM ATP, ADP, and AMP. The effect of AMP is assumed to be due to de novo formation of ADP. NaF (25 mM) blocks reactivation suggesting the involvement of a protein phosphatase in the activation process. At high nucleotide concentrations (3 mM) the enzyme is inactive. In the presence of Mg2+ ions nucleotide induced activation is further increased. Mg2+ ions themselves influence the equilibrium state of the enzyme complex. Low concentrations (1 mM) favor inactivation while high concentrations (10 mM) stimulate activation of the enzyme suggesting that Mg2+ ions may act by regulating the associated kinase and phosphatase.
mesh_terms: D042942:3-Methyl-2-Oxobutanoate Dehydrogenase (Lipoamide); D000227:Adenine Nucleotides / Q000494:pharmacology*; D000244:Adenosine Diphosphate / Q000494:pharmacology; D000249:Adenosine Monophosphate / Q000494:pharmacology; D000255:Adenosine Triphosphate / Q000494:pharmacology; D000596:Amino Acids / Q000494:pharmacology; D000818:Animals; D004044:Dietary Proteins / Q000494:pharmacology; D004789:Enzyme Activation / Q000187:drug effects; D004793:Enzyme Reactivators; D007658:Ketone Oxidoreductases / Q000037:antagonists & inhibitors / Q000378:metabolism*; D008274:Magnesium / Q000494:pharmacology; D008297:Male; D008929:Mitochondria, Heart / Q000201:enzymology; D008930:Mitochondria, Liver / Q000201:enzymology*; D009097:Multienzyme Complexes / Q000037:antagonists & inhibitors / Q000378:metabolism*; D051381:Rats; D011919:Rats, Inbred Strains; D012969:Sodium Fluoride / Q000494:pharmacology
chemical_list: D000227:Adenine Nucleotides; D000596:Amino Acids; D004044:Dietary Proteins; D004793:Enzyme Reactivators; D009097:Multienzyme Complexes; D000249:Adenosine Monophosphate; D000244:Adenosine Diphosphate; D000255:Adenosine Triphosphate; D012969:Sodium Fluoride; D007658:Ketone Oxidoreductases; D042942:3-Methyl-2-Oxobutanoate Dehydrogenase (Lipoamide); D008274:Magnesium