Reference
Glutamic Acid (Glutamate)
**Glutamic Acid (Glutamate)** is a nonessential amino acid that the human body synthesizes on its own, and which serves three distinct roles: the central nervous system's principal excitatory neurotransmitter, a key carrier of nitrogen between tissues, and the molecule responsible for the savory taste called umami.
Chemistry and naming
Glutamic acid is one of the 20 amino acids that make up dietary protein. It is classified as acidic because its side chain carries a second carboxyl group. At the pH of the body, that group is deprotonated, so the molecule exists almost entirely in its anionic form — glutamate. The two names refer to the same compound: “glutamic acid” describes the protonated molecule, “glutamate” the salt or ion. Monosodium glutamate (MSG) is its sodium salt.
Because the body manufactures glutamate from intermediates of central metabolism, it is considered nonessential — it does not have to be supplied by the diet. It remains one of the most abundant amino acids in most food proteins.
Biological roles
In the brain and spinal cord, glutamate is the dominant excitatory neurotransmitter, acting on receptors that mediate learning and memory. Dietary glutamate, however, is largely metabolized in the gut wall and does not freely cross the blood–brain barrier, so brain glutamate pools are regulated separately from intake.
Glutamate is also a hub of nitrogen metabolism. Through transamination reactions it accepts and donates amino groups, shuttling nitrogen between amino acids and feeding the urea cycle. It is closely related to glutamine, its amide form, into which it is readily converted. It is also a precursor to other amino acids, including proline and arginine.
Umami and food
Free glutamate stimulates the umami taste receptor, producing the savory depth associated with aged cheese, tomatoes, mushrooms, and broth. This is why glutamate-rich ingredients are used to round out flavor. In intact dietary protein the glutamate is bound within peptide chains and is not tasted as umami; the savory effect comes from the free, unbound form released during fermentation, ripening, or cooking.
Relevance to potato protein
Glutamate and glutamine are among the more abundant amino acids in plant proteins, though their proportions differ by source. In a randomized crossover comparison of potato, rice, and whey protein isolates, the plant-derived proteins produced a lower insulinaemic response and improved glucose maintenance than whey, with no significant difference in appetite ratings between the proteins (Nutrients, 2021, PMID:34201703). For a broader overview of how the amino acid composition shapes protein quality, see what potato protein is and how it is made.
Related terms