title: Hydrogen bonding controls excited-state decay of the photoactive yellow protein chromophore.
abstract: We have performed excited-state dynamics simulations of a Photoactive Yellow Protein chromophore analogue in water. The results of the simulations demonstrate that in water the chromophore predominantly undergoes single-bond photoisomerization, rather than double-bond photoisomerization. Despite opposite charge distributions in the chromophore, excited-state decay takes place very efficiently from both single- and double-bond twisted minima in water. Radiationless decay is facilitated by ultrafast solvent reorganization, which stabilizes both minima by specific hydrogen bond interactions. Changing the solvent to the slightly more viscous D(2)O leads to an increase of the excited-state lifetime. Together with previous simulations, the present results provide a complete picture of the effect of the protein on the photoisomerization of the chromophore in PYP: the positive guanidinium group of Arg52 favors double-bond isomerization over single-bond isomerization by lowering the barrier for double-bond isomerization, while the hydrogen bonds with Tyr42 and Glu46 enhance deactivation from the double-bond twisted minimum.
authors.affiliation: Laboratoire de Chimie et Physique Quantiques, IRSAMC, CNRS et Universite de Toulouse, Toulouse, France.
authors.forename: Martial
authors.initials: M
authors.lastname: Boggio-Pasqua
authors.forename: Michael A
authors.initials: MA
authors.lastname: Robb
authors.forename: Gerrit
authors.initials: G
authors.lastname: Groenhof
mesh_terms: D001120:Arginine / Q000737:chemistry / Q000235:genetics; D001426:Bacterial Proteins / Q000737:chemistry* / Q000235:genetics; D017666:Deuterium Oxide / Q000737:chemistry; D005453:Fluorescence; D006860:Hydrogen Bonding; D007536:Isomerism; D008163:Luminescent Measurements; D009154:Mutation; D055668:Photochemical Processes; D020283:Photoreceptors, Microbial / Q000737:chemistry* / Q000235:genetics; D014867:Water / Q000737:chemistry
chemical_list: D001426:Bacterial Proteins; D020283:Photoreceptors, Microbial; C050162:photoactive yellow protein, Bacteria; D014867:Water; D001120:Arginine; D017666:Deuterium Oxide