Induced Effects of Sodium Ions on Dopaminergic G-Protein Coupled Receptors
Figure 3
Free energy profile of sodium binding.
(A) Two-dimensional free energy profile for (z,χ2) reaction coordinates, where z is the z coordinate of the bound sodium ion and χ2 is the dihedral angle (CA-CB-CG-CD1) of tryptophan Trp6.48. The binding site a, b, c of the receptor show the pathway for sodium in the receptor and the locking of the tryptophan into the 100 degrees position (inactive state). The vertical white line shows the approximate position of Trp6.48. (B) Location of binding sites a, b, c in the D2 receptor. (C) Associated absolute free energy error map of the free energy profile of (A) computed by 25 metadynamics runs of 14 ns each (MD3). All basins have sub-kcal/mol error while only higher hills in the free energy surface show more significant variations.