Glutamic acid. Molecular model of the amino acid glutamic acid. Its chemical formula is C5.H9.N.O4. Atoms are represented as spheres and are colour- coded: carbon (blue), hydrogen (gold), nitrogen (dark blue) and oxygen (red). Amino acids are the building blocks of proteins. Glutamic acid is not an essential amino acid, so it does not need to be obtained from the diet. It has an important role in nerve function and brain signalling, where it is a precursor to the molecule GABA. GABA (gamma aminobutyric acid) is an inhibitory neurotransmitter (nerve signalling chemical) that is an integral component of the central nervous system (CNS).