Impact of substituent effects on the design of beta-sheet mimetics and beta-double helices from (E)-vinylogous gamma-amino acid oligomers

Abstract

Here we report the design, single crystal conformations, impact of the substituents and structural differences of two structurally important motifs, beta-sheets and beta-double helices. Though beta-sheets are common structural motifs in protein structures, beta-double helices are not common in proteins and peptides. We found that both beta-sheet mimetics and beta-double helices can be constructed from the homooligomers of alpha,beta-unsaturated gamma-amino acids. Results suggested that introducing gem-dialkyl substitutions at the gamma-carbon of the homooligomer of alpha,beta-unsaturated gamma-amino acids resulted in the beta-double helix conformation, while the same oligomer with monosubstitution at the gamma-carbon displayed a beta-sheet structure.