Synthesis of cyclic peptides and cyclic proteins via ligation of peptide hydrazides.

Intramolecular ligation of peptide hydrazides is reported to occur readily, causing the lactamization of fully unprotected peptides in an epimerization-free manner. This method relies on the routine procedures of Fmoc solid-phase peptide synthesis. It can be used to prepare cyclic peptides and cyclic proteins under simpler, mild conditions at lower costs.