Figure 2.

Structural and energetic changes associated with increasing the coordination of K⁺ ions bound to valinomycin. K⁺ ions complexed to valinomycin are in direct coordination with 6 carbonyl ligands. Increasing their coordination to 7 and 8 using n=1 and n=2 water molecules destabilizes the K⁺ complex. ΔΔg_n(ε) denotes this change in complexation energy, as determined from the reaction given by equation 3. ΔΔg_n(ε) are provided for two different values of ε, which are representative of the dielectric constant of the lipid membranes. Note that calculations using higher values of ε, such as ε=80, also result in a greater stability of the 6-fold coordination. RMSD_n reflects the change in the backbone structure of K⁺ bound valinomycin due to complexation by n water molecules.