Brain glutamine synthetase

Carl GF, Blackwell LK, Barnett EC, et al. 1993. Manganese and epilepsy Brain glutamine synthetase and liver arginase activities in genetically epilepsy prone and chronically seizured rats. Epilepsia 34 441-446. 

Rate constants were determined as follows ki was determined from the rate of clearance of [ N]ammonia from rat blood (Freed, B. R., and Cooper, A. J. L., unpublished results), kg was deduced by determining the best fit necessary to yield a BUI of 24% given a CBF of 100 mL/100 g/min (42) and a brain transit time of 3 s (39). kg was assumed to be one-half kg based on the known pH difference between the brain and the blood (48). k and kg were assumed to equal kg (i.e., no pH difference between small and large pools was assumed), kg (and 7) were calculated from the known activity of whole brain glutamine synthetase... 

Oliver, C.N., Starke-Reed, P.E., Stadtman, E.R., Liu, G.J., Carney, J.M. and Floyd, R.A. (1990). Oxidative damage to brain proteins, loss of glutamine synthetase activity, and production of free radicals during ischemia/reperfusion-induced injury to gerbil brain. Proc. Natl Acad. Sd. USA 87, 5144-5147. 

Glucosidase and 0-galactosidase (sweet almond emulsin)[36] Glutamine synthetase (native octameric brain) 371 Glycogen phosphorylase At3 ]... 

In earlier studies the in vitro transition metal-catalyzed oxidation of proteins and the interaction of proteins with free radicals have been studied. In 1983, Levine [1] showed that the oxidative inactivation of enzymes and the oxidative modification of proteins resulted in the formation of protein carbonyl derivatives. These derivatives easily react with dinitrophenyl-hydrazine (DNPH) to form protein hydrazones, which were used for the detection of protein carbonyl content. Using this method and spin-trapping with PBN, it has been demonstrated [2,3] that protein oxidation and inactivation of glutamine synthetase (a key enzyme in the regulation of amino acid metabolism and the brain L-glutamate and y-aminobutyric acid levels) were sharply enhanced during ischemia- and reperfusion-induced injury in gerbil brain. 

Martinez-Hernandez, A., Bell, K. P. and Norenberg, M. D. Glutamine synthetase glial localization in rat brain. Science 195 1356-1358,1977. 

Glutamine synthetase, a brain Mn enzyme, is located mainly in astrocytes, and its synthesis may be modulated by nitric oxide (496). Inhibition of this enzyme could be relevant to aging diseases (497). There is evidence that human NT2-N neurons die via ionotropic glutamate receptor-mediated mechanisms when exposed to hypoxia in the presence of glutamate (498). 

Martinez-Hernandez A, Bell KP, Norenberg MD (1977) Glutamine synthetase glial localization in brain. Science 195(4284) 1356-1358... 

Depletion of glutamate in the glutamine synthetase reaction may have additional effects on the brain. Glutamate and its derivative y-aminobutyrate (GABA see Fig. 22-29) are important neurotransmitters the sensitivity of the brain to ammonia may reflect a depletion of neurotransmitters as well as changes in cellular osmotic balance. ... 

Homogeneous preparations of glutamine synthetase are available from many sources including Escherichia coli, Salmonella typhimurium, peas, sheep brain, and rat liver. Glutamine synthetases from bacteria have 12... 

Suarez I., Bodega G., and Fernandez B. (2002). Glutamine synthetase in brain effect of ammonia. Neurochem. Int. 41 123-142. 

Norenberg, M.D., and A.Martinez-Hernandez. 1979. Fine structural localization of glutamine synthetase in astrocytes of rat brain. Brain Res. 161(2) 303—310. 

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