Yeast display technology enables rapid discovery of low-nanomolar macrocyclic peptide inhibitors of human angiotensin-converting enzyme 2

Macrocyclic peptides are valuable molecular formats for drug development, positioning themselves as a bridge between small-molecules and larger biologics due to their favourable pharmacological properties. Here we describe the discovery of low-nanomolar macrocyclic peptide inhibitors of human angiotensin-converting enzyme 2 (hACE2) by quantitatively screening millions of structurally diverse disulfide-cyclised peptide ligands using yeast display technology. The most potent yeast-encoded macrocyclic peptide exhibits a KD of 16.1 nM and inhibits hACE2 with an IC50 of 7.5 nM. These binding affinities and inhibitory potencies are comparable to those of other cyclic peptides discovered using well-established phage and mRNA display technologies. Determination of the crystal structure of the macrocyclic peptide in complex with hACE2 reveals a rigid β-hairpin structure that shows a different binding mode compared to previously reported inhibitors. Thus, yeast display is a valid technology to rapidly generate macrocyclic peptides with desired binding properties for the development of potential therapeutics.