We have just started doing electrostatic calculations with APBS. The problem we want to solve is to compare the electrostatic surface potential of a chitinase (1e15) with a 9 fold mutant of the same enzyme. When we look at the individual electrostatic maps in PyMol we can see differences between the two, but we would like to quantify and map the differences more precisely.
So far we have tried to compare the wt and mutant potentials by subtracting the mutant grid values from the corresponding wt value at the same grid points. We then visualize the result grid in PyMol to highlight the areas of difference (grid points with small differences between them are set to zero). Is this a possible solution to our problem? If not, any suggestions of other ways to proceed?