Modeling Light-Induced Chromophore Hydration in the Reversibly Photoswitchable Fluorescent Protein Dreiklang

• Published in: Molecules (Basel, Switzerland) Vol. 28; no. 2; p. 505
• Main Authors: Grigorenko, Bella L., Polyakov, Igor V., Nemukhin, Alexander V.
• Format: Journal Article
• Language: English
• Published: Switzerland MDPI AG 04.01.2023; MDPI
• Subjects: Crystal structure; excited-state properties; fluorescent proteins; Geometry; Green Fluorescent Proteins - chemistry; Hydration; hydration reaction; Light; Luminescent Proteins - chemistry; molecular modeling; photoswitching; protein Dreiklang; Proteins; Wire; hydration reaction; fluorescent proteins; molecular modeling; quantum chemistry; conical intersection points; excited-state properties; QM/MM; photoswitching; protein Dreiklang
• ISSN: 1420-3049; 1420-3049
• DOI: 10.3390/molecules28020505

We report the results of a computational study of the mechanism of the light-induced chemical reaction of chromophore hydration in the fluorescent protein Dreiklang, responsible for its switching from the fluorescent ON-state to the dark OFF-state. We explore the relief of the charge-transfer excited-state potential energy surface in the ON-state to locate minimum energy conical intersection points with the ground-state energy surface. Simulations of the further evolution of model systems allow us to characterize the ground-state reaction intermediate tentatively suggested in the femtosecond studies of the light-induced dynamics in Dreiklang and finally to arrive at the reaction product. The obtained results clarify the details of the photoswitching mechanism in Dreiklang, which is governed by the chemical modification of its chromophore.