Targeting diverse protein-protein interaction interfaces with α/β-peptides derived from the Z-domain scaffold

Peptide-based agents derived from well-defined scaffolds offer an alternative to antibodies for selective and high-affinity recognition of large and topologically complex protein surfaces. Here, we describe a strategy for designing oligomers containing both alpha- and beta-amino acid residues (alpha/beta-peptides) that mimic several peptides derived from the three-helix bundle Z-domainscaffold. We show that alpha/beta-peptides derived from a Z-domain peptide targeting vascular endothelial growth factor (VEGF) can structurally and functionally mimic the binding surface of the parent peptide while exhibiting significantly decreased susceptibility to proteolysis. The tightest VEGF-binding alpha/beta-peptide inhibits the VEGF165-induced proliferation of human umbilical vein endothelial cells. We demonstrate the versatility of this strategy by showing how principles underlying VEGF signaling inhibitors can be rapidly extended to produce Z-domain-mimetic alpha/beta-peptides that bind to two other protein partners, IgG and tumor necrosis factor-alpha. Because wellestablished selection techniques can identify high-affinity Z-domain derivatives from large DNA-encoded libraries, our findings should enable the design of biostable alpha/beta-peptides that bind tightly and specifically to diverse targets of biomedical interest. Such reagents would be useful for diagnostic and therapeutic applications.