Nitrogen, molecular, metabolic production

Hydrazine is metabolized by rat liver microsomal enzymes to unknown products, ultimately yielding molecular nitrogen (Timbrell et al., 1982 Jeimer Timbrell, 1995). This was dependent upon oxygen and NADPH and was increased by NADH in the presence of NADPH. Hydrazine metabolism was 20-70% lower in human microsomes prepared from three individuals compared with rats. Hydrazine is also metabolized by rat liver mitochondria, but the monoamine oxidase inhibitors clorgyline and pargyline do not significantly decrease this activity (Jenner Timbrell, 1995). 

Molecular mechanisms of nitrate accumulation depend not only on the nitrate reductase system, but also on the ability of roots to take from the soil, nitrate or ammonium ions, and on the plant s capacity for their conversion by assimilation processes to higher products. Besides this, the assimilation depends on the ability of a given genotype to transport substances necessary for the synthesis. It was shown that genotype differences of the nitrate reductase level do not depend on the nitrate content in tissues [25]. Nitrates are accumulated in plant organisms at high concentrations when aU the nitrogen accepted cannot be utilized for the production of amino acids and for subsequent protein synthesis [26]. This occurs when the plant, in the course of its metabolism, is unable to reduce the accepted nitrates into the assimilable ammonia form. 

Nitrogen (N) is a component of many biomolecules, especially of proteins and nucleic acids. Molecular N is reduced by certain free-living and symbiotic microorganisms (see Nitrogen fixation) to ammonia, which is the first and final product of nitrogen metabolism. 

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