Unraveling the similarity of the photoabsorption of deprotonated p-coumaric acid in the gas phase and within the photoactive yellow protein

Phys Chem Chem Phys. 2011 Jan 28;13(4):1585-9. doi: 10.1039/c0cp01075h. Epub 2010 Dec 6.

Abstract

Using advanced QM/MM methods, the surprisingly negligible shift of the lowest-lying bright electronic excitation of the deprotonated p-coumaric acid (pCA(-)) within the photoactive yellow protein (PYP) is shown to stem from a subtle balance between hypsochromic and bathochromic effects. More specifically, it is found that the change in the excitation energy as a consequence of the disruption of the planarity of pCA(-) inside PYP is nearly canceled out by the shift induced by the intermolecular interactions of the chromophore and the protein as a whole. These results provide important insights about the primary absorption and the tuning of the chromophore by the protein environment in PYP.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Absorption
  • Bacterial Proteins / chemistry*
  • Coumaric Acids / chemistry*
  • Gases / chemistry*
  • Halorhodospira halophila
  • Light*
  • Models, Molecular
  • Photochemical Processes
  • Photoreceptors, Microbial / chemistry*
  • Protein Conformation
  • Protons*
  • Quantum Theory

Substances

  • Bacterial Proteins
  • Coumaric Acids
  • Gases
  • Photoreceptors, Microbial
  • Protons
  • photoactive yellow protein, Bacteria