Computing electrostatic binding energy with the TABI Poisson-Boltzmann solver

Computations of the electrostatic binding energy Delta Delta G(elec) are presented for 51 solvated biomolecular complexes using the treecode-accelerated boundary integral (TABI) Poisson-Boltzmann solver. TABI computes the electric potential on the triangulated molecular surface of a complex and its monomers, and further processing yields the solvation free energy Delta G(solv) needed to compute Delta Delta G(elec). The accuracy of the TABI results was verified using the high-order finite-difference Matched Interface and Boundary (MIB) method as the reference. Among two codes used here for surface triangulation, MSMS and NanoShaper, the latter is found to be more accurate, efficient, and robust. It is shown that the accuracy of the computed Delta Delta G(elec) using TABI can be efficiently improved by extrapolating low triangulation density results to the high density limit. The calculations needed to compute Delta Delta G(elec) are susceptible to loss of precision due to cancellation of digits and this emphasizes the need for relatively higher accuracy in comput-ing Delta G(solv).