Coulombic electrostatic potential of GroEL-GroES chaperonin complex computed with the Chimera coulombic command. One of the 21 subunits is colored yellow. Electrostatic potential of -10 kT/e is red, 0 kT/e is white, 10 kT/e is blue.
The Chimera 1.6 command script 1aon-esp.cmd produces this coloring. It splits the 21 chain PDB model 1aon into a separate model for each chain because the molecular surface calculation for the full model fails. Surfaces and electrostatic potential are computed separately for each chain. Adding hydrogens, computing charges and potential takes about 10 minutes for this 59,000 atom structure.