Transamination of 3-phenylpyruvate in pancreatic B-cell mitochondria.
High aminotransferase activities catalyzing the reaction between L-glutamate and the aromatic ketomonocarboxylic acid, 3-phenylpyruvate, were observed in the mitochondria from pancreatic B-cells. At very low concentrations of 3-phenylpyruvate, L-glutamine was an effective amino group donor. The aminotransferase activities for the aliphatic ketomonocarboxylic acids, pyruvate and 2-ketoisovalerate, were lower in B-cell mitochondria. High rates of transamination of 2-ketoisocaproate with L-glutamine were observed and may be an important prerequisite for the insulin secretory potency of this 2-keto acid. Since B-cell mitochondria are well supplied with L-glutamine and L-glutamate, 3-phenylpyruvate-induced 2-ketoglutarate production may explain the insulin secretory potency of 3-phenylpyruvate which is not a fuel for pancreatic islet cells.
D000818:Animals; D002250:Carbon Radioisotopes; D005971:Glutamates / Q000378:metabolism; D018698:Glutamic Acid; D007515:Islets of Langerhans / Q000378:metabolism*; D007700:Kinetics; D051379:Mice; D008820:Mice, Obese; D008928:Mitochondria / Q000378:metabolism*; D010667:Phenylpyruvic Acids / Q000378:metabolism*; D013379:Substrate Specificity; D000637:Transaminases / Q000378:metabolism*
D002250:Carbon Radioisotopes; D005971:Glutamates; D010667:Phenylpyruvic Acids; D018698:Glutamic Acid; C040713:3-phenylpyruvate aminotransferase; D000637:Transaminases; C031606:phenylpyruvic acid