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Four Resonance Structures Elucidate Double-Bond Isomerisation of a Biological Chromophore

preprint
submitted on 17.02.2020 and posted on 19.02.2020 by Evgeniy Gromov, Tatiana Domratcheva
Photoinduced double-bond isomerisation of the chromophore of photoactive yellow protein (PYP) is highly sensitive to chromophore-protein interactions. On the basis of high-level ab initio calculations, using the XMCQDPT2 method, we scrutinise the effect of the chromophore-protein hydrogen bonds on the photophysical and photochemical properties of the chromophore. We identify four resonance structures – two closed-shell and two biradicaloid – that elucidate the electronic structure of the ground and first excited states involved in the isomerisation process. Changing the relative energies of the resonance structures by hydrogen-bonding interactions tunes all photochemical properties of the chromophore in an interdependent manner. Our study sheds new light on the role of the chromophore electronic structure in tuning in photosensors and fluorescent proteins.

History

Email Address of Submitting Author

evgeniy.gromov@mpimf-heidelberg.mpg.de

Institution

Max-Planck Institute for Medical Research Heidelberg

Country

Germany

ORCID For Submitting Author

0000-0003-1176-026X

Declaration of Conflict of Interest

There is no conflict of interests to be declared

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