Figure 1.

The structures and single amino acid code for the twenty naturally occurring amino acids. Each amino acid shares a carboxylic acid (−COOH) and a primary amine group (−NH₂). The properties of the individual amino acids are governed by the nature and functionality of the R-group attached to the α-carbon. Researchers exploit the differences in individual amino acid units to develop peptide-based therapeutics. Of particular importance to antimicrobial peptides and peptide self-assembly is the hydrophobic: hydrophilic balance of the primary peptide structure.