Theoretical and Computational Chemistry

Computational Modeling Reveals the Mechanism of Fluorescent State Recovery in the Reversibly Photoswitchable Protein Dreiklang

Authors

Abstract

The unique properties of the photoswitchable protein Dreiklang are attributed to a reversible hydration/dehydration reaction at the imidazolinone ring of the chromophore. Recovery of the fluorescent state, which is associated with a chemical reaction of chromophore dehydration, is an important part of the photocycle of this protein. Here we characterize the fluorescent (ON) and non-fluorescent (OFF) states of Dreiklang and simulate the thermal recovery reaction OFF → ON using computational approaches. By using molecular modeling methods including the quantum mechanics/molecular mechanics (QM/MM) technique, we characterize the structures and spectra of the ON- and OFF-states. The results are consistent with relevant experimental data. The computed reaction profile explains the observed recovery reaction and clarifies the mechanism of chemical transformations in the chromophore-containing pocket in Dreiklang.

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