MD simulations of in silico mutations of α7/AChBP in the presence of Ca²⁺ ions. (a) Time evolution of the all-atom RMSD of the E158A mutant of the α7/AChBP pentamer in the presence of Ca²⁺ ions. (b) Structure of the E158A mutant of α7/AChBP with bound Ca²⁺ ions at the conclusion of a 150-ns MD simulation. View is from the top of the pentamer, with Ca²⁺ ions shown as purple spheres at each subunit interface. (c) Ca²⁺ ion bound to one subunit interface of the E158A mutant is shown with key stabilizing residues depicted in stick representation; view is from the side of the pentamer. (d) Time evolution of the interatomic distances between the associating Ca²⁺ ion and the oxygen atoms of key stabilizing residues from the C-loop and F-loop during the course of MD simulation. (e and f) Time evolution of the interatomic distances between the Ca²⁺ ion and the oxygen atoms of key stabilizing residues from the C-loop and F-loop from the E185Q and D160S mutants during the course of MD simulation.