Metabolism nitrogen

Smirnova and Moshkov have investigated the effects of the removal of leaves or buds and of grafting on the alkaloidal content of lupins, and Wallebroek has studied the alkaloidal and nitrogenous metabolism of Lupinus luteus seeds on germination. ... 

Numerous studies have shown that increased levels of UV affect photosynthetic activity (10-23), growth rate (24), nitrogen metabolism (25), and locomotion (26) of phytoplankton. Additionally, increases in UV-B are likely to alter community diversity as well as phytoplankton species composition. Thus, by weakening the base of the food web and altering trophodynamic relationships, UV-induced changes could potentially have far-reaching effects on the entire ecosystem. 

Figure 11.3 is a flow model representing in extremely simple form the main relevant features of nitrogen metabolism. It is not difficult to propose a sufficient explanation why Bprot is isotopically heavier than the diet. We might expect that the net effect of transamination and deamination of amino acids is to remove isotopically lighter N (Macko et al. 1987). That is to say, we may expect that the equilibrium constant for the reaction ... 

Finally, an outline of how the same approach to modeling can be applied to questions of nitrogen metabolism and to food chains in ecosystems is presented. We would argue that the value of such an approach lies at least as much in helping to better define issues, and in suggesting new, testable hypotheses, than in providing explanations which may rest on oversimplified assumptions. 

Ahmad, I., Larher, F., Mann, A.F., McNally, S.F. Stewart, G.R. (1982). Nitrogen metabolism of halophytes. IV. Characteristics of glutamine synthetase from Triglochin maritima L. New Phytologist, 91, 585-95. 

Transamination channels a-amino acid nitrogen into glutamate. L-Glutamate dehydrogenase (GDH) occupies a central position in nitrogen metabolism. 

Figure 11 The different steps of nitrogen metabolism in the extraradical hyphae, ccto-mycorrhizal roots, and roots of the host plant. I, absorption 2, assimilation 3. storage 4. translocation A, extramatrical hyphae B. ectomycorrhizal sheath C, Hartig net D, root cortical cells AA amino. acids.

A. Johansen, R. D. Finlay, and P. A. Olsson, Nitrogen metabolism of external hy-phae of the arbuscular mycorrhizal fungus Glomus intraradices. New Phytol. 133 705 (1996). 

F. Martin and B. Botton, Nitrogen metabolism of ectomycorrhizal fungi and ecto-mycorrhiza. Adv. Plant Pathol. 9 83 (1993). 

Yudkoff, M., Daikhin,Y., Nissim, I., Jawad,A.,Wilson, J. and Batshaw, M. B. In vivo nitrogen metabolism in ornithine transcarbamylase deficiency. /. Clin. Invest. 98 2167-2173, 1996. 

Fresh and stored yams were examined for protein and selected nitrogen-metabolizing enzymes. Yams stored at room temperature lost weight (water), protein, and non-protein nitrogen. Sprouting depleted all of the protein. The major protein of yams is a 60-70%... 

Because yams are poor sources of dietary nitrogen, a knowledge of nonprotein nitrogen metabolism in yams would provide useful information for retaining the amount present in fresh tubers and preventing the usual losses suffered during storage in... 

Nitrogen metabolism Sulfur metabolism Lipid Metabolism... 

Fig. 3. Examples of the KEGG pathway diagrams a portion of the two-component signal transduction pathway and a portion of the metabolic pathway for nitrogen metabolism both in Escherichia coli.

Cheung, C.W., Cohen, N.G., Raijman, L. (1989). Channeling of urea cycle intermediates in situ in permeabilized hepatocytes. J. Biol. Chem. 264,4038-4044. Cohen, P.P. (1954). Nitrogen metabolism of amino acids. In Chemical Pathways in Metabolism (Greenberg, D.M., Ed.), Vol. 2, pp. 1-46. Academic Press, New York. Fisher, R.B. (1954). Protein Metabolism. Methuen, London. 

Kestens, P.J. (1964). La Perfusion du Foie Isole. Editions Arscia S.A. Bruxelles. Meyer, AJ. Lamers, W.H., Chamulead, R.A.F.M. (1990). Nitrogen metabolism and ornithine cycle fixation. Physiol. Rev. 70, 701-748. 

Urea ((NH2)2CO), a small and highly water soluble molecule, is an end product of amine and ammonia nitrogen metabolism and as such represents an example of biodetoxification (Section 6.4). The process is discussed in this section because it illustrates a genuine de novo biosynthetic pathway rather than detoxification involving chemical modification, via phase I and phase II reactions, of a pre-existing molecule as is the case for haem or steroid hormones. 

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