NLM DIR Seminar Schedule

Abstract:

Biomolecular systems are dense collections of charged molecules, many of them quite complex, embedded in a solution of water and ions of various types. Consequently, electrostatic interactions are extremely important in determining the behavior of these systems. Despite many decades of research, accurate and rigorous calculation of these interactions is still a major hurdle. We will apply a recently developed theory, rigorous at the Debye-Hückel level, of electrostatic interactions in the presence of ions to a pair of model systems: 1) a system of charged polarizable spheres with arbitrary sizes, charge distributions (arbitrary multipole moments), and dielectric constants; and 2) a system of charged planes that represent the close approach of charged biomolecules. We will show that asymmetric screening, the extra repulsion between charged dielectric objects in a high dielectric constant solvent that was discovered in the ion-free situation, is still present when ions are included. We will discuss the importance of many-body effects, which are included in the present theory but not in commonly used pairwise approximations. We will also briefly indicate a pathway to investigating ion-specific effects (the Hoffmeister effect) in which ions with the same charge have different behavior. And we will also briefly mention efforts to extend the comparison of classical electrostatic interactions to quantum calculations from S type atoms to more a more general setting.