NMetabolism - NITROGEN METABOLISM Nitrogen is essential for...

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Unformatted text preview: NITROGEN METABOLISM Nitrogen is essential for all organisms (in amino acids and nucleic acids). oxidative Most of the conversions between organic and inorganic nitrogen are catalyzed by bacterial and archaeal enzymes. reductive fungi plants animals Nitrate reductase, nitrite reductase Ammonium assimilation glutamate dehydrogenase NADPH -KG NH4+ NADP+ gl u H2O Ammonium assimilation Glutamine synthetase GOGAT (glutamine oxo-glutarate amino transferase) ATP NH4+ ADP + Pi GS glu gln NAD+ or Fd(ox) NADH Fd(red) GOGAT glu -KG Glutamate and glutamine are major –NH2 donors through transaminases e.g., Glu +OAA -KG + Asp Glutamate and glutamine are major –NH2 donors through transaminases e.g., Glu +OAA -KG + Asp Urea cycle: removal of excess N Pre-urea cycle: formation of carbamyl phosphate Urea cycle: Lose two amino-N and a CO2 How much energy does it take to remove two amino-nitrogens? How many of the reactions that we have studied are represented in excretion of excess nitrogen? Summary •Nitrogen enters the biophere through plants, fungi, but mainly bacteria and archaea •Plants, fungi, and bacteria reduce nitrate nitrogen to ammonium •Ammonium is incorporated into organic molecules by glutamate dehydrogenase and glutamine synthase/GOGAT •Other amino acids are formed by transamination •The urea cycle removes nitrogen from ammonia and alanine as urea ...
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This note was uploaded on 11/24/2011 for the course BIS 105 taught by Professor Kennethhilt during the Spring '09 term at UC Davis.

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