Chromophore Protonation State Controls Photoswitching of the Fluoroprotein asFP595
Figure 1
(A) Chromophore (MYG) in the trans conformation and adjacent amino acid side chains. Ser158, Glu215, and the crystallographic water molecule W233 are hydrogen-bonded to MYG (dashed lines). His197 is π-stacked to the MYG phenoxy-moiety and forms a hydrogen bond to Glu215 (dashed line). The carbon skeleton of the quantum mechanical (QM) subsystem is shown in cyan, and the carbon atoms modelled by molecular mechanics (MM) are shown in orange. (B) Schematic drawings of the different MYG protonation states considered in this work.