Local electrostatic optimization in proteins

A simple electrostatic model has been used to investigate theextent to which the structure of protein molecules is organizedto optimize the internal electrostatic interactions. We findthat the model provides a favorable total intra-protein electrostaticenergy for almost all polar and charged groups of atoms, suggestinga high degree of structural optimization. By contrast, a significantfraction of individual group–group interactions are foundto be unfavorable. An analysis as a function of the range ofinteractions included shows the electrostatic organization isgenerally relatively short range (up to 6 or 7 Å betweengroup centers). Although the model is very simple, it is usefulfor assessing the overall quality of protein experimental structures,for pin-pointing some types of errors and as a guide to improvingprotein design.