Glutamine synthetase distribution

Potato tubers Tissue-specific distribution of glutamine synthetase Pereira et al. (20)... 

Pereira S, Pissarra J, Sunkel C, Salema R. Tissue-specific distribution of glutamine synthetase in potato tubers. Ann Bot 1996 77 429-432. 

Electron paramagnetic resonance (continued) cobalt-thermolysin complex, 28 334, 335 exchange reactions, 31 106-107 glutamine synthetase, 28 358-364 invisible oxygen species, 31 94-95 metalloenzymes, 28 324, 326 metal particle size distribution, 36 99-100, 104... 

Norenberg MD (1979) The distribution of glutamine synthetase in the rat central nervous system. J Histochem Cytochem 27 756-762. 

Thus ammonia assimilation is going on in the plant in different tissues at the same time often at rates higher than that of N reduction. The ubiquitous distribution of high levels of glutamine synthetase in plant tissues are necessary to prevent the build up of toxic ammonia levels. 

A literature search revealed that the distribution of the enzymes of nitrate assimilation had been determined in one case and was apparently as predicted by the theory. Nitrate and nitrite reductases were shown by isolation of mesophyll and bundle-sheath protoplasts to be predominantly in mesophyll cells. In addition, the enzymes of ammonium assimilation (glutamine synthetase and glutamate synthase) were also found mainly in these cells (see Edwards and Huber, ref. 9), rather than in the Kranz cells. No conclusions were drawn about the significance of such a distribution. 

The following three characteristic mammalian liver and kidney enzymes are absent from muscle catalase, xanthine oxidase, and D-amino oxidase. The distribution of many other enzymes in mammals is limited to particular organs. Thus arginase occurs only in the liver, alkaline phosphatase in the intestinal mucosa, acid phosphatase in kidney, spleen, and prostate, 5-nucleotidase in the testis, and a-mannosidase in the epididymis (see Table 4.6). The blood is disproportionately rich in carbonic anhydrase, and the pancreas in ribonuclease. Glutamine synthetase, which condenses... 

T2. Tatibana, M., and Ito, K., Control of pyrimidine biosynthesis in mammalian tissues. 1. Partial purification and characterization of glutamine utilising carbamyl phosphate synthetase of mouse spleen and its tissue distribution. J. Biol. Chem. 244, 5403-5413 (1969). 

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