Figure 2.

Electron densities for the β₂AR ligands obtained using the Complex-LCP method. 2mF _o − DF _c electron densities in the ligand-binding pocket (purple circle) right after molecular replacement are shown as superimposed meshes contoured at 0.7σ (timolol, green; alprenolol, red; carvedilol, blue; propranolol, cyan). The mF _o − DF _c polder ligand OMIT maps (Liebschner et al., 2017 ▸) contoured at 3σ are shown for each ligand inside blue (transient ligand alprenolol) and green (transient ligand timolol) boxes. The inset in the black box demonstrates cross-validation of the ligand exchange using crystallographic data. When alprenolol-to-timolol exchange data are refined with alprenolol, the residual mF _o − DF _c electron density (green) contoured at 3σ clearly indicates that the transient ligand has been successfully exchanged.