Making Circles: Recent Advance in Chemical and Enzymatic Approaches in Peptide Macrocyclization

Abstract

Macrocyclic peptides have emerged as an important class of molecules for drug discovery due to their enhanced stability and bioavailability. Since the 1990s, ligation chemistries have been extensively studied for preparing peptide macrocycles. The ligation chemistries usually go through an energetically favored capture coupled with an acyl transfer reaction to overcome the disfavored entropy ring formation and facilitate the formation of the cyclic amide bond. Concurrently with chemical methods, several enzymatic approaches utilizing peptide ligases have also been explored. These peptide ligases are enzymes that involve in the production of naturally-occurring cyclic peptides in diverse organisms. Many enzymes have been isolated and proved to be highly efficient in the production of cyclic peptides. Here, we review the recent advance in chemical ligation and enzymatic approaches in making cycles.