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Regulation of glutaminase ec 3.5.1.2 by exogenous glutamate ammonia and 2 oxo glutarate in synaptosomal enriched preparation from rat brain


, : Regulation of glutaminase ec 3.5.1.2 by exogenous glutamate ammonia and 2 oxo glutarate in synaptosomal enriched preparation from rat brain. Neurochemical Research 7(6): 667-678

Phosphate-activated glutaminase in synaptosomal-enriched preparation from rat brain is very sensitive to inhibition by low concentration of glutamate, NH3 and 2-oxoglutarate when added to the incubation medium at pH 7.6. By increasing the concentration of either of these compounds up to 0.5 mM, a pronounced initial inhibition is followed by little or no further effect when the concentration is increased beyond this level. By lowering the pH of the reaction mixture to 7.0, the inhibition by glutamate is almost abolished and that of NH3 reduced. Glutamate inhibits mainly the N-ethylmaleimide-sensitive fraction of glutaminase which previously was suggested to be localized to the outer phase of the mitochondrial inner membrane, whereas NH3 inhibits both the N-ethylmaleimide-sensitive and -insensitive fraction. The inhibition by 2-oxoglutarate is caused by glutamate formation by aminotransferase reactions. Since 2-oxoglutarate is produced by the tricarboxylic acid cycle, the operation of this cycle may regulate the glutaminase reaction by controlling glutamate formation via the aminotransferase reactions.

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Related references

Kvamme, E.; Lenda, K., 1982: Regulation of glutaminase by exogenous glutamate, ammonia and 2-oxoglutarate in synaptosomal enriched preparation from rat brain. Phosphate activated glutaminase in synaptosomal enriched preparation from rat brain is very sensitive to inhibition by low concentration of glutamate, ammonia and 2-oxoglutarate when added to the incubation medium at pH 7.6. By increasing the conc...

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