Secondary structures of P-peptides:The unnatural behaviour of beta-sheet

摘要

Structure investigation of potential drugs is an important step of rational drug design.Results are published on the biological activity and cell penetrating ability of beta-peptides.In contrast to natural amino acids,p-amino acids have an additional torsional angle in the backbone(mu).This additional torsional angle makes mapping of beta-amino acids rather complex.For the simplest P-peptide,HCO-beta-Ala-NH_2(or HCO-HGly-NH_2),14 conformers were found at the RHF/3-21G level of theory,almost three times as many as for HCO-Gly-NH_2.Similar to alpha-peptides,secondary structures are mainly built from these monomer conformers,and from some other conformers which cannot be stabilized in a monomer.Thus,numerous secondary structures,helical and non-helical were studied.However,secondary structures of larger beta-peptides or beta-peptide assemblies are hardly observed.Here we present theoretical results on P-sheet structures of larger systems containing 16 beta-amino acids in four separate strands.