Amide I vibrational circular dichroism of polypeptides: Generalized fragmentation approximation method

Jun Ho Choi, Joong Soo Kim, Minhaeng Cho

Research output: Contribution to journalArticlepeer-review

53 Citations (Scopus)


Fragment analyses of vibrational circular dichroic response of dipeptides were carried out recently [Choi and Cho, J. Chem. Phys. 120, 4383 (2004)]. In the present paper, by using a minimal size unit peptide containing two chiral carbons covalently bonded to the peptide group, a generalized fragmentation approximation method is discussed and applied to the calculations of infrared-absorption and vibrational circular dichroism (VCD) intensities of amide I vibrations in various secondary structure polypeptides. Unlike the dipole strength determining IR-absorption intensity, the rotational strength is largely determined by the cross terms that are given by the inner product between the transition electric dipole and the transition magnetic dipole of two different peptides. This explains why the signs and magnitudes of VCD peaks are far more sensitive to the relative orientation and distance between different peptide bonds in a given protein. In order to test the validity of fragmentation approximation, three different segments in a globular protein ubiquitin, i.e., right-handed α -helix, Β -sheet, and Β -turn regions, were chosen for density-functional theory (DFT) calculations of amide I vibrational properties and the numerically simulated IR-absorption and VCD spectra by using the fragmentation method are directly compared with DFT results. It is believed that the fragmentation approximation method will be of use in numerically simulating vibrational spectra of proteins in solutions.

Original languageEnglish
Article number174903
JournalJournal of Chemical Physics
Issue number17
Publication statusPublished - 2005 May

Bibliographical note

Funding Information:
This work was supported by the Creative Research Initiatives Program of KOSEF.

ASJC Scopus subject areas

  • General Physics and Astronomy
  • Physical and Theoretical Chemistry


Dive into the research topics of 'Amide I vibrational circular dichroism of polypeptides: Generalized fragmentation approximation method'. Together they form a unique fingerprint.

Cite this