Dear all,

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?

Yours sincerely,