The contour electrostatic potential map for chosen amino-acid side chains from the lysozyme structure for experimental (Exp) and theoretical electrostatic potential maps (TAAM, based on the transferable aspherical atom model; IAM, based on the independent atom model) for the structure with PDB code 5k7o. eTAAM and eIAM maps were calculated using the electron scattering factors, whereas xTAAM and xIAM maps were calculated using the X-ray scattering factors. All of the maps are calculated at 1.8 Å resolution. The voxel values of all theoretical maps are scaled to the standard deviation of the experimental density map and the average value of zero, and their σ contours are then shown. The maps take thermal smearing effects into account (with B).