Aspartic acid. Molecular model of the amino acid aspartic acid. Its chemical formula is C4.H7.N.O4. Atoms are represented as balls and are colour- coded: carbon (blue), hydrogen (gold), oxygen (red) and nitrogen (dark blue). Amino acids are the building blocks of proteins. Aspartic acid is a non-essential amino acid. It can be synthesised by the body and so does not need to come from the diet. Aspartic acid plays an important role in nerve function and acts as an excitory neurotransmitter (a chemical that stimulates nerve cells). It also participates in gluconeogenesis, a process by which where glucose (a type of sugar used by the body for energy) is formed from simple molecules such as pyruvate and lactic acid.