Protein a-Turns Recreated in Structurally Stable Small Molecules

α-Turn mimics: α-Turns in proteins vary in three sets of (ϕ, ψ) angles that determine peptide backbone shape and helical pitch. Structures of cyclic tetrapeptides 1 and 2 are shown to closely match two α-turn types that are structurally influential at key sites in 20 proteins described. NMR and CD spectroscopy as well as MD simulations have been used to characterize these first examples of non-helical α-turns created in small molecules.