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biopax3:comment |
Authored: 2003-04-29 00:00:00,
Edited: D'Eustachio, P, 0000-00-00 00:00:00,
These reactions mediate the synthesis of aspartate, asparagine, glutamate, and glutamine from ammonia and intermediates of glycolysis, and allow the utilization of the carbon atoms from these four amino acids for glucose synthesis under fasting conditions.<P>These reactions also provide a means to collect nitrogen, both as ammonia and as amino groups, and direct it towards urea synthesis. Transamination, the conversion of an amino acid to the corresponding alpha-keto acid coupled to the conversion of a molecule of alpha-ketoglutarate to glutamate, is the first step in the catabolism of most amino acids. Transamination reactions are freely reversible so they also provide a means to balance concentrations of various amino acids and alpha-keto (2-oxo) acids in the cytosol.
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