Aspartic Acid

Definition

Aspartic acid, shown in Fig. 1, is one of the 20 protein amino acids. Its three-letter symbol is Asp and one letter symbol is D. It is a monoaminodicarboxylic acid, and it is classified as an acidic amino acid. Aspartic acid has the lowest isoelectric point (pI) 2.77 of the protein amino acids. It is among the five amino acids that were detected in Miller’s electric discharge experiment in 1953 and is found in extracts from carbonaceous chondrites. Since it has two carboxyl groups (α- and β-carboxyl group), it can make both α- and β-peptide bonds with other amino acids. In biosynthesis of proteins, only α-peptide bonds are formed. As the racemization of aspartic acid is relatively rapid, the D/L ratio of aspartic acid can be used for dating biological materials such as bone.

Fig. 1

Structural formula of aspartic acid