EurekaMag.com logo
+ Site Statistics
References:
52,725,316
Abstracts:
28,411,598
+ Search Articles
+ Subscribe to Site Feeds
EurekaMag Most Shared ContentMost Shared
EurekaMag PDF Full Text ContentPDF Full Text
+ PDF Full Text
Request PDF Full TextRequest PDF Full Text
+ Follow Us
Follow on FacebookFollow on Facebook
Follow on TwitterFollow on Twitter
Follow on Google+Follow on Google+
Follow on LinkedInFollow on LinkedIn

+ Translate

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

Regulation of glutaminase ec 3.5.1.2 by exogenous glutamate ammonia and 2 oxo glutarate 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, 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.


Accession: 006288114



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...

Watanabe A.; Shiota T., 1992: Effect of ammonia and other putative neurotoxic substances on glutaminase activity in synaptosomal mitochondria from rat cerebrum and brain stem. Ammonia, methanethiol and caprylate inhibited glutaminase activity of the synaptosomal mitochondria from the cerebrum and brain stem of rats. These neurotoxic substances might cause hepatic encephalopathy by decreasing the synthesis and release of...

Svenneby, G., 1971: Glutaminase dependent glutamate and ammonia synthesis in the brain. Nordisk Medicin 85(21): 667-667

Kisfaludy, S., 1975: Effects of ammonia intoxication and liver injury on rat brain glutamate-dehydrogenase and glutaminase activity. Glutamate dehydrogenase (GDH) and glutaminase activity in the rat brain was altered by chronic ammonia intoxication, subacute liver injury induced by CCl4 or digalactosamine, and the combination of them. GDH activity was found to increase consider...

Hochreiter, M.C.; Patek, D.R.; Schellenberg, K.A., 1972: Catalysis of alpha imino glutarate formation from alpha keto glutarate and ammonia by bovine glutamate dehydrogenase. Journal of Biological Chemistry 247(19): 6271-6276

Hogstad S.; Svenneby G.; Torgner I.A.; Kvamme E.; Hertz L.; Schousboe A., 1988: Glutaminase in neurons and astrocytes cultured from mouse brain kinetic properties and effects of phosphate glutamate and ammonia. Phosphate activated glutaminase comprises two kinetically distinguishable enzyme forms in cultures of cerebellar granule cells, of cortical neurons and astrocytes. Specific activity of glutaminase is higher in cultured neurons compared with astroc...

Stokke O.; Goodman S.I.; Moe P.G., 1976: Inhibition of brain glutamate decarboxylase by glutarate glutaconate and seta hydroxy glutarate explanation of the symptoms in glutaric aciduria. Clinica Chimica Acta 66(3): 411-415

Plaitakis, A.; Zaganas, I., 2001: Regulation of human glutamate dehydrogenases: implications for glutamate, ammonia and energy metabolism in brain. Glutamate dehydrogenase (GDH) catalyzes the oxidative deamination of glutamate to alpha-ketoglutarate using NAD or NADP as cofactors. In mammalian brain, GDH is located predominantly in astrocytes, where it is probably involved in the metabolism o...

Plaitakis, A.; Zaganas, I., 2001: Regulation of human glutamate dehydrogenases: Implications for glutamate, ammonia and energy metabolism in brain. Glutamate dehydrogenase (GDH) catalyzes the oxidative deamination of glutamate to alpha-ketoglutarate using NAD or NADP as cofactors. In mammalian brain, GDH is located predominantly in astrocytes, where it is probably involved in the metabolism o...

Wallace, D.R.; Dawson, R., J., 1992: Ammonia regulation of phosphate-activated glutaminase displays regional variation and impairment in the brain of aged rats. The regulation of PAG by ammonia in whole brain (Sprague-Dawley) and regional (Fischer-344) synaptosomal preparations from adult and aged animals was assessed. Whole brain synaptosomal preparations from both age groups displayed a significant decr...