Glutamic acid

(CC) Image: David E. Volk
Glutamic acid, one of the common alpha-amino acids.

Glutamic acid, also called glutamate and abbreviated as Glu or E, is one of the twenty common amino acids used by living organisms to build proteins. It is one of only two acidic amino acids, the other being aspartic acid, and it is similar to glutamine which has an amide function in place of the acid. Being hydrophilic, glutamate is often found on the surfaces of proteins. Glutamate also serves as an energy source in the brain.