Long-range electrostatic contributions to protein-ligand binding estimatedusing protein charge ladders, affinity capillary electrophoresis, and continuum electrostatic theory

Affinity capillary electrophoresis and protein charge ladders are used toge ther to measure the contributions of long-range electrostatic interactions to binding of substituted benzene sulfonamide inhibitors to derivatives of human carbonic anhydrase II. The results are analyzed by continuum electros tatic calculations, which afford a detailed analysis of interactions of ind ividual members of a population from a charge ladder. A Monte Carlo simulat ion of the experimental data using calculated contributions of individual l ysine side chains to inhibitor binding shows that a large number of differe nt patterns of acetylation are consistent with the experimental results. Th e calculations predict significant differences in the contributions of some lysines to Delta G and simulations suggest that experimental resolution mu st be enhanced to be able to measure such differences.