Computation of ionic distributions around charged biomolecular structures: results for right-handed and left-handed DNA.

We introduce an efficient computational methodology employing the potentials of mean force approach for estimating the detailed three-dimensional ionic distributions around arbitrarily complex charged biomolecular structures for all monovalent salt concentrations of practical interest (e.g., 0.1-5.0 M NaCl). Such distributions are required for specifying thermodynamic and structure-specific features of ion-mediated interactions of charged proteins, DNA and RNA, membranes, and macromolecular assemblies. As a first application, we present results for distributions around the B and ZI conformers of the DNA oligomer d(C-G)18.d(C-G)18. The ionic microenvironment depends strongly on the DNA conformation, sequence, and bulk salt concentrations.