Roles of ammonia

Prior to description of the cycle, it should be noted that ammonia has several important roles in the cell, which include the following  

Glutamate is required for the synthesis of some non-essential amino acids and key compounds such as glutathione. 

Functional Biochemistry in Health and Disease by Eric Newsholme and Tony Leech 2010 John Wiley Sons Ltd 

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A complex was detected in these solutions with the composition CuCN but this was not formed in significant quantities under the conditions employed. The role of ammonia molecules could not be assessed, although it was found that the rate showed a strong inverse dependence in ammonia concentration, indicating competition between NHj and CN for coordination sites. 

Leitner NKV (1998) Chlorination and formation of organoiodinated compounds the important role of ammonia. Environ Sci Technol 32 1680-1685. 

Despite these important roles of ammonia, the concentration in cells, and particnlarly in the blood, is maintained low (Table 10.1). Althongh many cells produce ammonia. 

Reference 85 presents the thermodynamic side of the previous paper. It is pointed out that although both ammonia and thiourea are present in the solution, because of the much higher stability constant of the Ag-thiourea complexes compared to the Ag-ammines, essentially all the Ag will be present as a thiourea complex. In this case, it can be assumed that the role of ammonia is only to control pH. 

Pitts, R.F. 1971. The role of ammonia production and excretion in regulation of acid-base balance. N. Engl. J. Med. 284(l) 32-38. 

Another application of quantum chemical methods is the investigation of the fundamental chemical behaviour of molecular systems potentially relevant to nu-cleation. Within the field of tropospheric nucleation mechanisms, two questions which have merited considerable study under the last decade are the modeling of the hydration of sulfuric acid, and the role of ammonia in sulfuric acid-water nucleation. 

The role of ammonia in water-sulfuric acid nucleation... 

Quantum chemical methods are valuable tools for studying atmospheric nucle-ation phenomena. Molecular geometries and binding energies computed using electronic structure methods can be used to determine potential parameters for classical molecular dynamic simulations, which in turn provide information on the dynamics and qualitative energetics of nucleation processes. Quantum chemistry calculations can also be used to obtain accurate and reliable information on the fundamental chemical and physical properties of molecular systems relevant to nucleation. Successful atmospheric applications include investigations on the hydration of sulfuric acid and the role of ammonia, sulfur trioxide and/or ions... 

The Role of Ammonia in the Reductive Half-Reaction Mechanism of Methanol Dehydrogenase... 

CavicchioK, R., DeMaere, M. Z., et at. (2007). Metagenoinic studies reveal the critical and wide ranging ecological importance of imcultivated archaea the role of ammonia oxidizers. Bioessays 29, 11-14. 

Grippon, P, Le Poncin-Lafltte, M., Boschat, M., Wang, S., Faure, G., Dutertre, D., Opolon, P Evidence for the role of ammonia in the intracerebral transfer and metabolism of tryptophan. Hepatology 1986 6 682 - 686... 

Walker, C.O., Schenker, S. Pathogenesis of hepatic encephalopathy with special reference to the role of ammonia. Amer. J. Clin. Nutr. 1970 23 619-632... 

The role of ammonia oxidation was studied more comprehensively [73]. From the experimental results it was suggested that ammonia adsorption takes place at two types of sites located on the (010) and (100) planes. V-O-V groups were found to be responsible for the SCR reaction whereas the V=0 sites promote the direct oxidation of ammonia to NO and the formation of N2O from the reaction of NO and ammonia. However, it is stressed here that these studies were carried out with unsupported materials. 

Senanayake, G. (2005). Catalytic role of ammonia in the anodic oxidation of gold in copper-free thiosulfate solutions. Hydrometallurgy, 77(3-4), 287-293. doi 10.1016/j.hydromet.2004.12.003... 

Benjamin AM, Quastel JH (1975) Metabolism of amino acids and ammonia in rat brain cortex slices in vitro a possible role of ammonia in brain function. J Neurochem 25 197-206. 

Clark EC, Nath KA, Hostetler MK, et al. 1990. Role of ammonia in tubulointerstital injury. Miner Electrolyte Metab 16(5) 315-321. 

Thomas G, Parks G (2006), Potential Roles of Ammonia in a Hydrogen Economy - A Study of Issues Related to the Use of Ammonia on-board Vehicular Hydrogen Storage, Washington, DC, US Department of Energy. 

Ferris, J.P. and Nicodem, D.E., 1972. Ammonia photolysis and the role of ammonia in chemical evolution. Nature, 238 268—269. 

The possible physiological role of ammonia as a nitrogen donor for ribosylamine phosphate synthesis has been studied and debated. Although ammonia can react nonenzymatically with PP-ribose-P to form riboiqrl-amine phosphate (IS), it can also react enzymatically to form this product in cell extracts (H, 15) and in intact cells (16, 17). Although most work supports the role of PP-ribose-P amidotransferase as the enzyme involved, Reem (18) has put forward evidence that a separate enzyme might use ammonia exclusively. 

Bykhovsky VY and Zaitseva NI (1977) Role of ammonia nitrogen in the biosynthesis of vitamin B12 by Propionibacterium shermanii. Prikl Biokhim Mikrobiol 13 16-23... 

The addition of NH3 to the Pd/FeCls system has also been reported [81-83]. Since no pyridine was added in these reactions, it is not clear if the role of ammonia is simply to substitute pyridine as a ligand or if it also is involved in the reaction analogously to the aforementioned primary amines. Although the use of ammonia may be economically more advantageous than the one of pyridine, these systems appear to be less active than the corresponding pyridine-promoted ones. 

Lietti L, Nova I, Forzatti P (2008) Role of ammonia in the reduction by hydrogen of NOx stored over Pt-Ba/Al203 lean NOx trap catalysts. J. Catal. 257 270-282... 

The role of ammonia is in buffering acid and it makes a contribution which is particularly important when the acid load is high. Ammonia produced in the tubular cell cytoplasm diffuses readily across the tubular cell membrane into the tubular fluid. Cell membranes consist largely of lipid material and so are in general permeable to non-polar particles such as ammonia The solubility of ionized particles such as ammonium ions in lipid is very low so that ions permeate cell membranes very slowly. 

In this section the salient features of carbide and nitride synthesis will be presented first. The role of ammonia and methane/hydrogen as reductant in the development of surface area will be discussed next, with references to the significance of pseudomorphic and topotactic phenomena in these transformations. 

The utilization of in sim generated aryl azides is not restrictive to [3+2] Huisgen condensation-type reactions. These compounds could also play the role of ammonia surrogate for the synthesis of aniline derivatives. Thus in 2004 Fu, Qiao and co-workers described conditimis involving Cul with or without DMEDA L26... 

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