Dipeptide structure determination by vibrational circular dichroism combined with quantum chemistry calculations

Kyung Koo Lee, Kwang Im Oh, Hochan Lee, Cheonik Joo, Hogyu Han, Minhaeng Cho

Research output: Contribution to journalArticlepeer-review

22 Citations (Scopus)


The solution structure and the local solvation environments of alanine dipeptide (AD, 1 a) and its isotopomer (AD*, 1 b, 13C on the acetyl end C=O) are studied by using infrared (IR) spectroscopy and vibrational circular dichroism (VCD). From the amide I IR spectra of AD* in various protic solvents, it is found that each of the two carbonyl groups is fully H-bonded to two water molecules. However, the number of alcohol molecules H-bonded to each C=O varies from one to two, and the local solvation environments are asymmetric around the two peptides of AD* in alcohol solutions. The amide I VCD spectra of AD and AD* in D2O are also measured, and a series of density functional theory (DFT, B3LYP/6-311 + + G**) calculations are performed to obtain the amide I normal-mode rotational strengths of AD and the intrinsic rotational strengths of its two peptide fragments. By combining the VCD-measurement and DFT-calculation results and employing a coupled oscillator theory, we show that the aqueous-solution structure of the dipeptide can be determined. We believe that the present method will be of use in building up a library of dipeptide solution structures in water.

Original languageEnglish
Pages (from-to)2218-2226
Number of pages9
Issue number15
Publication statusPublished - 2007 Oct 22


  • Circular dichroism
  • Density functional calculations
  • IR spectroscopy
  • Peptides
  • Structure elucidation

ASJC Scopus subject areas

  • Atomic and Molecular Physics, and Optics
  • Physical and Theoretical Chemistry


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