Abstract
Abstract Recently, neutron crystallography of the enhanced green fluorescent protein (EGFP) has revealed that a heavy water molecule directly hydrogen-bonded to the chromophore of EGFP, DOD323, has a longer bond length than other heavy water molecules. This remarkable elongation of bond length is because of intrinsic electrostatic potential inside EGFP, but its physicochemical origin has not been fully understood, yet. To clarify the phenomenon, we theoretically investigated the effect of residues surrounding the chromophore on the hydrogen-bonded structure around the chromophore with multi-component density functional theory. We focused on Arg96, Thr203, and Glu222, which are directly hydrogen-bonded to the chromophore. We theoretically confirmed that Arg96 and Thr203 affect the geometric asymmetrization of DOD323 quantitatively. Arg96 and Thr203 also stabilize the anionic (deprotonated) form of the chromophore, and the absence of even one of the residues causes proton/deuteron transfer from the neighboring His148. Our results suggest that Arg96 and Thr203 have a significant effect on the charge states of the chromophore and His148.
Published Version
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