MCELLBI 100B Lecture Notes - Lecture 22: Nitrogen Fixation, Haber Process, Nitrogenase
3 May 2020
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Dinitrogen 2nh3 (ammonia/ammonium: very stable, inert, 78% of atmosphere, can"t be used by most of life. The nitrogen fixation process is very difficult to do, haber process, required high temperature and pressure or can use nitrogenase. Nitrogen: essential for amino acids, toxic to cells, no storage polymer beyond proteins. Proteins (amino acids) are also a fuel source: lots of energy available in protein, these proteins found in muscles, critical machines that keep us running. In general, not great to break down the proteins as a nutritional source. Dietary proteins are hydrolyzed by proteases: pepsin (cleaves n-term to l,f,w,y) hydrophobic, bulky residues, trypsin (cleaves c-term to k,r, chymotrypsin (cleaves c-term to f,w,y, aminopeptidase, carboxypeptidase. Aminotransferase reaction is the critical reaction to know. In the cell, an amino acid alpha keto group and an alpha amino group are roughly equivalent: equilibrate between 2 states as long as you have the additional reactants. Aminotransferase: core reaction allows us to move amine groups around.
