An acidic amino acid with the formula HOOC(CH2
) COOH. Glutamic acid plays a central role in the cell's nitrogen metabolism. Along with glutamine it is the primary product of nitrogen assimilation, being formed from α-ketoglutaric acid by reductive addition of ammonia. Some amino acids are formed directly from glutamate (e.g. proline, ornithine), while others receive their amino group from glutamate in a *transamination
reaction. Glutamate is also a precursor in the synthesis of purines, pyrimidines, and porphyrins. In amino acid catabolism, glutamate is formed in transamination reactions with other amino acids. The carbon skeleton of these amino acids can then be further broken down, while the glutamate can undergo oxidative phosphorylation to reform α-ketoglutarate.