β-Aminopeptidases: Insight into Enzymes without a Known Natural Substrate

β-Aminopeptidases are unique enzymes found in a diverse range of microorganisms that can utilize synthetic β-peptides as a sole carbon source. Six β-aminopeptidases have been previously characterized with preferences for different β-amino acid substrates and have demonstrated the capability to catalyze not only the degradation of synthetic β-peptides but also the synthesis of short β-peptides. Identification of other β-aminopeptidases adds to this toolbox of enzymes with differing β-amino acid substrate preferences and kinetics. These enzymes have the potential to be utilized in the sustainable manufacture of β-amino acid derivatives and β-peptides for use in biomedical and biomaterial applications. This is important, because β-amino acids and β-peptides confer increased proteolytic resistance to bioactive compounds and form novel structures as well as structures similar to α-peptides. The discovery of new enzymes will also provide insight into the biological importance of these enzymes in nature.