Structurally sensitive anharmonic Calpha-D stretch vibration in deuterated peptides.
In the present study, vibrational properties of the Calpha-D stretching mode in deuterated alanine dipeptide are examined by ab initio normal-mode calculations. A backbone conformational scan reveals a quite similar structural sensitivity of the harmonic and anharmonic vibration frequencies for both the fundamental and overtone transitions. The distributions of the frequencies are found to be linearly anticorrelated with that of the Calpha-D bond length, with the latter being found to be also structurally sensitive. Theory predicts that, as determined by the quantum mechanical anharmonic force field, the highly anharmonic (with a mean diagonal anharmonicity of 48.0 cm(-1)) and yet highly localized Calpha-D stretching mode shall be potentially useful in probing peptide local structures and dynamics.
Wang
Jianping
J
Beijing National Laboratory for Molecular Sciences, Molecular Reaction Dynamics Laboratory, Institute of Chemistry, Chinese Academy of Sciences, Beijing 100190, People's Republic of China. jwang@iccas.ac.cn