title: Understanding the Amide-II Vibrations in β-Peptides.
abstract: In this work, the vibrational characteristics of the amide-II modes in β-peptides in five helical conformations, namely, 8-, 10-, 12-, 14-, and 10/12-helices, have been examined. Remarkable conformational dependence of the amide-II spectral profile is obtained by ab initio computations as well as modeling analysis. Intramolecular hydrogen-bonding interaction and its influence on backbone structure and on the amide-II local-mode transition frequencies and intensities are examined. Through-space and through-bond contributions of the amide-II vibrational couplings are analyzed, and it was found that hydrogen-bonding interaction is not a determining factor for the coupling strength. The results reported here provide useful benchmarks for understanding experimental amide-II infrared spectra of β-peptides and suggest the potential application of this mode on monitoring the structures and dynamics of β-peptides.
authors.affiliation: Beijing National Laboratory for Molecular Sciences; Laboratory of Molecular Reaction Dynamics, Institute of Chemistry, Chinese Academy of Sciences , Beijing 100190, P. R. China.
authors.forename: Juan
authors.initials: J
authors.lastname: Zhao
authors.affiliation: Beijing National Laboratory for Molecular Sciences; Laboratory of Molecular Reaction Dynamics, Institute of Chemistry, Chinese Academy of Sciences , Beijing 100190, P. R. China.
authors.forename: Jianping
authors.initials: J
authors.lastname: Wang
mesh_terms: D000577:Amides / Q000737:chemistry*; D006860:Hydrogen Bonding; D010455:Peptides / Q000737:chemistry*; D011487:Protein Conformation
chemical_list: D000577:Amides; D010455:Peptides