MBIO 3280 Lecture Notes - Lecture 15: Flavodoxin, Nitrogen Fixation, Nitrogenase
21 Oct 2017
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Document Summary
Converting n2 to nh3: limiting step for providing usable nitrogen to biosphere. Nitrogenase is the key enzyme complex ** Converting nh3 to organic nitrogen: nh3 is the immediate product of nitrogen fixation, also acquired from environment directly or by reduction of no3, at neutral ph exists mostly as ammonium ion nh4+ In cells, nh3 is usually incorporated into organic compounds by formation of glutamate or glutamine, which donate amines for synthesis of amino acids and nucleotides. Converting organic nitrogen to nh3: most microbes can do this, the nh3 used for biosynthesis or released into environment. In the environment, nh3 is: generally stable under anoxic conditions, volatile in oxic environments, mostly protonated at neutral ph and tends to bind to negatively charged clay particles in soil, taken up by plants and other microbes. Oxidizing nh3 to no3- : a two-step process: usually steps are performend by different organisms.
