Figure 3.

Direct and synchronous observation of protein conformational dynamics and ligand binding on an individual Maltose Binding Protein to decipher the mechanism of action. (A) Cartoon representation depicting the existing equilibrium between an open and closed state and ligand binding preferentially to the open state; (B) Three color smFRET traces depicting the binding of Cy7-maltose to an open and partially closed state of MBP as open and solid arrowheads; (C) Correlation plot of Cy3-Cy5 FRET efficiencies both at the binding and dissociation points for the binding events of single Cy7-maltose showing the relative distribution of the four possible scenarios; type I, binding to an open state and dissociation from the same state; type II, binding to an open state and dissociation from a partially closed state; type III, binding to a partially closed state and dissociation from an open state; and type IV, binding to a partially closed state followed by dissociation from the same state. (Figure 3 adapted from [102] with permission).