CH 461 Lecture Notes - Lecture 17: Glutamine Synthetase, Glutamate Dehydrogenase, Carbamoyl Phosphate
Document Summary
Ammonia is toxic at high concentrations, even though ammonium ion, nh 4 + is an intermediate in many reactions. For its utilization, ammonia must be incorporated into organic forms, transferred, and then incorporated into other compounds, for example, amino acids and nucleotides. The amino acids glutamine and glutamate and the compound carbamoyl phosphate are the key intermediates of nitrogen assimilation, leading to different classes of compounds. Glutamate dehydrogenase has a relatively high k m for ammonia. K m, means that this system operates most effectively when ammonia is relatively abundant. Incorporation of ammonia uses reducing equivalents: glutamate dehydrogenase: Glutamine synthetase requires atp energy for ammonia incorporation, using glutamate as an acceptor. Glutamine can be a precursor for the synthesis of glutamate, with the reaction of glutamate synthase, also known as gogat (glutamine: 2 oxyglutarate aminotransferase). The preceding reactions indicate that two ways exist of making glutamate: glutamate dehydrogenase or glutamine synthetase + glutamate synthase.
