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, α-ketoglutarate, and glutamate during palmitate oxidation, and also by assaying14C-products of [1-14C]palmitate oxidation. Oxidation of palmitate (or [1-14C]palmitate) resulted in the formation of aspartate (or14C-aspartate), and the oxidation was inhibited by aminooxyacetate (an inhibitor of transaminase), Palmitate oxidation also resulted in α-ketoglutarate formation, which was sensitive to the effect of aminooxyacetate. Addition of NH4Cl was found to increase14C-products and formation of α-ketoglutarate, whereas glutamate formation was not increased unless the rate of palmitate oxidation was reduced by 50% by aminooxyacetate or α-ketoglutarate was added exogenously. Exogenous α-ketoglutarate was found to decrease14C-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 α-ketoglutarate, however, α-ketoglutarate was not available for glutamate formation via glutamate dehydrogenase. We discuss the possibility that this was because (a) oxidative decarboxylation of α-ketoglutarate to form succinyl-CoA was favored over glutamate formation for the competition for α-ketoglutarate in the same pool, and (b) the pool of α-ketoglutarate produced in the aspartate aminotransferase reaction did not serve as substrate for glutamate formation.
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Kawamura, N. Study of amino acid formation during palmitate oxidation in rat brain mitochondria. Neurochem Res 14, 9–15 (1989). https://doi.org/10.1007/BF00969751
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DOI: https://doi.org/10.1007/BF00969751