N metabolism

Btaiche IF, Khalidi N. Metabolic complications of parenteral nutrition in adults, part 1 and part 2. Am J Health-Syst Pharm 2004 61 1938-1949, 2050-2059. 

Chiba K, Trevor A, Castagnoli N. Metabolism of the neurotoxic tertiary amine, MPTP, by brain monoamine oxidase. Biochem Biophys Res Commun 1984 120 547-578. 

Sudhakar-Barik and Sethunathan, N. Metabolism of nitrophenols in flooded soils. J. Environ. Qual, 7(3) 349-352, 1978a. 

Sudhakar-Barik, Siddaramappa, R., and Sethunathan. N. Metabolism of nitrophenols by bacteria isolated from parathion-amended flooded soil. Antonie van Leeuwenhoek, 42(4) 461-470,1976. 

Shimoi, K., Saka, N., Kaji, K., Nozawa, R., and Kinae, N., Metabolic fate of Inteolin and its functional activity at focal site, Biofactors, 12, 181, 2000. 

Interest centers on fluoroacetic acid itself,54-55,56 115 but its monofluorinated homologs have been equally studied to attempt to verify the observation that only compounds CFH2(CH2)nC02H with n = 0 or even numbers, and their derivatives (esters, salts) show considerable toxicity (Table 11) in addition to that of their acid function. In the course of in vivo metabolism these fluorinated derivatives end up, like any fatty acid by /(-oxidation or hydrolysis, as the toxic fluoroacetic acid. With an uneven number of n, metabolism stops at the stage of the less toxic 2-fluoropropanoic acid (CFH2CH2C02H). 

N intake - (fecal N - metabolic N) - (urine N -endogeneous urinary N)... 

Amino acids, amino groups, amino sugars, and nucleic acid derivatives usually account for >95% of the organic N in soils (Anderson et al., 1989), and many other N-containing compounds have been reported in trace amounts (Stevenson, 1994). Anderson et al. (1989) have found traces of L-phosphatidic acid, choline, ethanol-amine, and uric acid (the end product of N metabolism of many animals), which can be oxidized to allantoin, cyanuric acid, and urea. 

Pyridoxine is a component of several enzyme systems involved in N metabolism. In general, diets provide an adequate amount, in the free form or combined with phosphate. Some feedstuffs such as linseed and certain varieties of beans may contain pyridoxine antagonists. Pyridoxine is one of the vitamins that suffers during feed processing, 70-90% of the content in wheat being lost during milling (Nesheim, 1974). A severe deficiency results... 

Yamane, H., Murofushi, N., Osada, H., and Takahashi, N. Metabolism of Gibberellins in Early Immature Bean Seeds, Phytochemistry. 1977, 16, pp. 831-835. 

Wiedemuth, K., Muller, J., Kahlao, A., Amine, S., Mock, H.P., Grzam, A., Hell, R., Egle, K., Beschow, H., and Humbeck, K., Successive maturation and senescence of individual leaves during barley whole plant ontogeny reveals temporal and spatial regulation of photosynthetic function in conjunction with C and N metabolism, J. Plant Physiol., 162, 1226-1236, 2005. 

Ravindranath, F. and Chandrasekhara, N., Metabolism of curcumin — studies with [3H]-curcumin, Toxicol., 22, 337, 1981. 

In contrast to zinc, the crucial role of Fe in the bioenergetics of carbon (C) and N metabolism is well recognized (e.g., Morel et al., 1991 Sunda, 1989). Substantial amounts of Fe are required in both photosynthetic and respiratory electron transport chains (e.g., Raven, 1988), the synthesis of chlorophyll (Chereskin and Castelfranco, 1982), and the assimilation ofNOj. Theoretical calculations based on Fe utilization efficiencies and cellular metabolic Fe demands, predict that phytoplankton growing on NOJ require 60% more Fe than those growing on NH (Raven, 1988, 1990), and greater cellular Fe requirements for NO growth have indeed been demonstrated for laboratory cultures of diatoms (Maldonado and Price, 1996). The extra Fe is needed to reduce NO to NH4 before it can be incorporated into amino acids. This process requires the assimilatory enzymes nitrate reductase (requires one... 

Otero, A., and Vincenzini, M. (2004). Nostoc (Cyanophyceae) goes nude Extracellular polysaccharides serve as a sink for reducing power under unbalanced C/N metabolism. J. Phycol. 40, 74—81. 

Much of the N-metabohsm of marine cyanobacteria observes the same basic scheme as that known for widely studied freshwater species (see Flores and Herrero 1994 Herrero et al., 2001 for reviews). Nitrogen acquisition and metabolism in marine cyanobacteria are finely tuned to photosynthetic activity, the availability of additional nutrients, and other environmental factors. Most, if not all, of N-metabolism is funnelled through the GS—GOGAT pathway which—on balance—links ammonium... 

A number of other enzymes deserve consideration because they are involved in pathways that are closely linked to nitrogen metabolism, such as Rubisco and other carboxylases that are critical to the coupling of C and N metabolism (Huppe and Turpin, 1994), or electron transport system (ETS) enzymes such as isocitrate dehydrogenase that are involved in respiratory metabolism (Roy and Packard, 2001). Others are relevant to N losses (e.g., esterases that are used as indices of cell lysis Agusti et al., 1998 or proteases associated with active cell death processes, e.g., Berman-Frank et al, 2004) (Table 32.1). 

Inhibitors have been used not only to identify pathways of N metabolism but also to distinguish between uptake and assimilation of inorganic N. For example, MSX is an irreversible inhibitor of GS and has been used to explore the role of N assimilation products (e.g., gin) and intracellular NH4 on the feedback inhibition of processes such as nitrogenase activity and NOa uptake (Arp and Zumft, 1983). In addition, the protonophore carbonyl cyanide m-chlorophenylhydrazone (CCCP) has been used to distinguish between uptake and assimilation of NH4 in marine algae (Rees et al., 1998). 

Table 10.2 Mass shifts in common Phase n metabolism ...

Y.K. Wang, Z. Ma, D.F. Quiim, F.W. Fu, Inverse N-metabolic labelling-MS for comparative proteomics and rapid identification of protein markers/targets. Rapid Commun. Mass Spectrom., 16 (2002) 1389. 

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