Infrared probing of 4-Azidoproline conformations modulated by azido configurations

Kyung Koo Lee, Kwang Hee Park, Cheonik Joo, Hyeok Jun Kwon, Jonggu Jeon, Hyeon Il Jung, Sungnam Park, Hogyu Han, Minhaeng Cho

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15 Citations (Scopus)


4-Azidoproline (Azp) can tune the stability of the polyproline II (P II) conformation in collagen. The azido group in the 4R and 4S configurations stabilizes and destabilizes the P II conformation, respectively. To obtain insights into the dependence of the conformational stability on the azido configuration, we carried out Fourier transform (FT) IR experiments with four 4-azidoproline derivatives, Ac-(4R/S)-Azp-(NH/O)Me. We found that the amide I and azido IR spectra are different depending on the azido configuration and C-terminal structure. The origin of such spectral differences between 4R and 4S configurations and between C-terminal methylamide and ester ends was elucidated by quantum chemistry calculations in combination with 1H NMR and time- and frequency-resolved IR pump-probe spectroscopy. We found that the azido configurations and C-terminal structures affect intramolecular interactions, which are responsible for the ensuing conformational and thereby IR spectral differences. Consequently, 4-azidoproline conformations modulated by azido configurations can be probed by IR spectroscopy. These findings suggest that 4-azidoproline can be both a structure-control and -probing element, which enables the infrared tracking of proline roles in protein structure, function, and dynamics.

Original languageEnglish
Pages (from-to)5097-5110
Number of pages14
JournalJournal of Physical Chemistry B
Issue number17
Publication statusPublished - 2012 May 3


ASJC Scopus subject areas

  • Physical and Theoretical Chemistry
  • Materials Chemistry
  • Surfaces, Coatings and Films

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