FIGURE 3.

ITC titration curves for the binding of nicotine (A), cytisine (B), and varenicline (C) to AcAChBP are provided. Nicotine binding data were recorded on a VP-ITC instrument, whereas cytisine and varenicline binding data were recorded on an ITC200 instrument. The thermodynamic profiles for nicotine, cytisine, and varenicline binding to AcAChBP (D) are displayed as a bar chart with Gibb's energy (ΔG°) in blue and the enthalpic (ΔH°) and entropic contributions (−TΔS°) in red and in green, respectively. A similar bar chart representation is provided for the comparison of nicotine binding to Ac-, Ls-, and BtAChBPs (E).