Amino Acid Synthesis from α-Ketoglutarate

Consider the metabolic pathway involved in the synthesis and degradation of amino acids. Glutamate is a crucial amino acid that plays a significant role in nitrogen metabolism and serves as a precursor for the synthesis of several other amino acids. One of the key enzymes involved in the conversion of glutamate to other amino acids is glutamate dehydrogenase (GDH). This enzyme catalyzes the reversible oxidative deamination of glutamate to α-ketoglutarate and ammonia, utilizing NAD+ as a cofactor.

The activity of GDH can be regulated by various factors including pH, substrate concentration, and allosteric effectors. In conditions of high ammonia concentration, GDH is stimulated to promote the conversion of glutamate to α-ketoglutarate, thus facilitating the removal of excess nitrogen. However, in conditions where the energy status of the cell is low, the activity of GDH is inhibited.

Based on this information, which of the following amino acids could potentially be synthesized from the intermediate product α-ketoglutarate in the presence of appropriate nitrogen sources?