Brownian dynamics simulations of ion atmospheres around polyalanine and B-DNA: effects of biomolecular dielectric.
We have extended an earlier Brownian dynamics simulation algorithm for simulating the structural dynamics of ions around biomolecules to accommodate dielectric inhomogeneity. The electrostatic environment of a biomolecule immersed in water was obtained by numerically solving the Poisson equation with the biomolecule treated as a low dielectric region and the solvent treated as a high dielectric region. Instead of using the mean-field type approximations of ion interactions as in the Poisson-Boltzmann model, the ions were treated explicitly by allowing them to evolve dynamically under the electrostatic field of the biomolecule. This model thus accounts for ion-ion correlations and the finite-size effects of the ions. For a 13-residue alpha-helical polyalanine and a 12-base-pair bp B-form DNA, we found that the choice of the dielectric constant of the biomolecule has much larger effects on the mean ionic structure around the biomolecule than on the fluctuational and dynamical properties of the ions surrounding the biomolecule.
Department of Chemistry and Biochemistry, University of California, San Diego, 9500 Gilman Drive, La Jolla, CA 92093-0365, USA.
David S
DS
Cerutti
Chung F
CF
Wong
J Andrew
JA
McCammon
D000465:Algorithms; D003198:Computer Simulation; D004247:DNA / Q000737:chemistry*; D004563:Electrochemistry; D007477:Ions / Q000737:chemistry; D008956:Models, Chemical; D010455:Peptides / Q000737:chemistry*; D017433:Protein Structure, Secondary
D007477:Ions; D010455:Peptides; C019529:polyalanine; D004247:DNA