Peptide Cyclization Methodologies Amenable to in Vitro Display

Display technology platforms offer their own unique set of challenges for chemical transformations, at the heart of which lies peptide macrocyclization. The amenable reactions for peptide macrocyclization on this platform need to meet a number of criteria like high reactivity, selectivity, mild conditions, irreversibility, and in many cases, a unique requirement to be assimilated into the translation machinery. Skillful utilization of these reactions has led to the formation of huge macrocyclic peptide libraries with varied linkages and topographies which have in turn led to the discovery of a number of hits for purposes such as drug discovery and others. Herein, we review those reactions which have mainly been applied in mRNA and phage display and discuss their technical characteristics and significance.