Physical Chemistry

Interplay Between Locally Excited and Charge Transfer States Governs the Photoswitching Mechanism in Fluorescent Protein Dreiklang


We present the results of high-level electronic structure and dynamics simulations
of the photoactive protein Dreiklang. With the goal to understand the details of
Dreiklang's photocycle, we carefully characterize the excited states of the ON- and
OFF-forms of Dreiklang. The key ?nding of our study is the existence of a lowlying
excited state of a charge-transfer (CT) character in the neutral ON form and
that population of this state, which is nearly isoenergetic with the locally excited
(LE) bright state, initiates series of steps ultimately leading to the formation of
the hydrated dark chromophore (OFF state). These results allow us to re?ne the
mechanistic picture of the Dreiklang's photocycle and photoactivation.


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Supplementary material

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dreiklang si draft