Unraveling the similarity of the photoabsorption of deprotonated p-coumaric acid in the gas phase and within the photoactive yellow protein.
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.
The Lundbeck Foundation Center for Theoretical Chemistry, Department of Chemistry, University of Aarhus, DK-8000 Aarhus C, Denmark.
Tomás
T
Rocha-Rinza
Kristian
K
Sneskov
Ove
O
Christiansen
Ulf
U
Ryde
Jacob
J
Kongsted
D000042:Absorption; D001426:Bacterial Proteins / Q000737:chemistry*; D003373:Coumaric Acids / Q000737:chemistry*; D005740:Gases / Q000737:chemistry*; D020607:Halorhodospira halophila; D008027:Light; D008958:Models, Molecular; D055668:Photochemical Processes; D020283:Photoreceptors, Microbial / Q000737:chemistry*; D011487:Protein Conformation; D011522:Protons; D011789:Quantum Theory
D001426:Bacterial Proteins; D003373:Coumaric Acids; D005740:Gases; D020283:Photoreceptors, Microbial; D011522:Protons; C050162:photoactive yellow protein, Bacteria