Vibrational assignment of the 4-hydroxycinnamyl chromophore in photoactive yellow protein

J Phys Chem B. 2007 Mar 15;111(10):2719-26. doi: 10.1021/jp066434j. Epub 2007 Feb 21.


Photoactive yellow protein (PYP) is a bacterial photoreceptor containing a 4-hydroxycinnamyl chromophore. We report the Raman spectra for the dark state of PYP whose chromophore is isotopically labeled with 13C at the carbonyl carbon atom or at the ring carbon atoms. Spectra have been also measured with PYP in D2O where the exchangeable protons are deuterated. Most of the observed Raman bands are assigned on the basis of the observed isotope shifts and normal mode calculations using a density functional theory. We discuss the implication for the analysis of the infrared spectra of PYP. The comprehensive assignment provides a satisfactory framework for future investigations of the photocycle mechanism in PYP by vibrational spectroscopy.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Bacterial Proteins / chemistry*
  • Binding Sites
  • Carbon Isotopes
  • Crystallization
  • Halorhodospira halophila
  • Molecular Structure
  • Photoreceptors, Microbial / chemistry*
  • Spectroscopy, Fourier Transform Infrared
  • Spectrum Analysis, Raman


  • Bacterial Proteins
  • Carbon Isotopes
  • Photoreceptors, Microbial
  • photoactive yellow protein, Bacteria