β-Peptides Synthesized by Way of Enzymes

Researchers have used enzymes for the first time to couple β-amino acids to other β-amino acids and to peptides. β-Amino acids have backbones one carbon atom longer than those of familiar α-amino acids. They are of interest as elements of β-peptides, which are oligomers that resist enzymatic breakdown and therefore have potential as oral drugs. Earlier this year, Dieter Seebach of the Swiss Federal Institute of Technology, Zurich, and coworkers found a new genus of microorganisms that possess peptidase enzymes that cleave β-amino acids from the N-termini of peptides. Now, Seebach and colleagues have used the reversible enzymes to join β-amino acids and to attach β-amino acids to peptides (Chem. Biodiv. 2007, 4, 2016). Use of the enzymes could have advantages over chemical techniques for β-peptide syntheses, such as improved regio- and stereoselectivity, reduced need for protecting groups, and mild reaction conditions.