1. Two pathways for glutamate synthesis.
Two pathways for glutamate synthesis. The left panel shows the GDH pathway, and the right panel shows the cyclic GS-GOGAT pathway. The basic characteristics of the two pathways are shown in the box below the scheme. The GDH pathway consists of a single enzyme, glutamate dehydrogenase (GDH). One net glutamate is produced from the reductive amination of 2-oxoglutarate; no ATP is involved, and GDH had a relatively low affinity for ammonium. The cyclic GS-GOGAT pathway consists of two enzymes, i.e., glutamine synthetase (GS) and glutamate synthase (GOGAT), which, in a cyclic configuration in effect, also produces one net glutamate by reductive amination of 2-oxoglutarate. However, one ATP is invested for every amino group assimilated, and GS has a relatively high affinity for ammonium.
Wally C. van Heeswijk et al. Microbiol. Mol. Biol. Rev. 2013; doi: /MMBR