title: Study of amino acid formation during palmitate oxidation in rat brain mitochondria.
abstract: The interrelation of palmitate oxidation with amino acid formation in rat brain mitochondria has been investigated in purified mitochondria of nonsynaptic origin by measuring the formation of aspartate, alpha-ketoglutarate, and glutamate during palmitate oxidation, and also by assaying 14C-products of [1-14C]palmitate oxidation. Oxidation of palmitate (or [1-14C]palmitate) resulted in the formation of aspartate (or 14C-aspartate), and the oxidation was inhibited by aminooxyacetate (an inhibitor of transaminase). Palmitate oxidation also resulted in alpha-ketoglutarate formation, which was sensitive to the effect of aminooxyacetate. Addition of NH4Cl was found to increase 14C-products and formation of alpha-ketoglutarate, whereas glutamate formation was not increased unless the rate of palmitate oxidation was reduced by 50% by aminooxyacetate or alpha-ketoglutarate was added exogenously. Exogenous alpha-ketoglutarate was found to decrease 14C-products, but not aspartate formation. These results indicated that palmitate oxidation was closely related to aspartate formation via aspartate aminotransferase. During palmitate oxidation without aminooxyacetate or added alpha-ketoglutarate, however, alpha-ketoglutarate was not available for glutamate formation via glutamate dehydrogenase. We discuss the possibility that this was because (a) oxidative decarboxylation of alpha-ketoglutarate to form succinyl-CoA was favored over glutamate formation for the competition for alpha-ketoglutarate in the same pool, and (b) the pool of alpha-ketoglutarate produced in the aspartate aminotransferase reaction did not serve as substrate for glutamate formation.
authors.affiliation: Department of Neurology, Johns Hopkins University School of Medicine, Baltimore, Maryland 21205.
authors.forename: N
authors.initials: N
authors.lastname: Kawamura
mesh_terms: D000625:Aminooxyacetic Acid / Q000494:pharmacology; D000818:Animals; D001224:Aspartic Acid / Q000378:metabolism*; D001921:Brain / Q000378:metabolism*; D005971:Glutamates / Q000378:metabolism*; D018698:Glutamic Acid; D007656:Ketoglutaric Acids / Q000378:metabolism*; D008928:Mitochondria / Q000187:drug effects / Q000378:metabolism*; D010084:Oxidation-Reduction; D010168:Palmitates / Q000378:metabolism*; D010169:Palmitic Acids / Q000378:metabolism*; D051381:Rats; D011919:Rats, Inbred Strains; D013347:Subcellular Fractions / Q000378:metabolism
chemical_list: D005971:Glutamates; D007656:Ketoglutaric Acids; D010168:Palmitates; D010169:Palmitic Acids; D000625:Aminooxyacetic Acid; D001224:Aspartic Acid; D018698:Glutamic Acid