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Divalent cations and the electrostatic potential around DNA: Monte Carlo and Poisson–Boltzmann calculations
Author(s) -
Pack George R.,
Wong Linda,
Lamm Gene
Publication year - 1999
Publication title -
biopolymers
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.556
H-Index - 125
eISSN - 1097-0282
pISSN - 0006-3525
DOI - 10.1002/(sici)1097-0282(199906)49:7<575::aid-bip4>3.0.co;2-j
Subject(s) - chemistry , divalent , monte carlo method , ion , poisson–boltzmann equation , counterion , thermodynamics , computational chemistry , chemical physics , physics , organic chemistry , statistics , mathematics
The predictions of counterion condensation theory for divalent ions were tested by comparison with the results of Monte Carlo calculations on an all‐atom model of DNA. Monovalent–divalent competition at the polyelectrolyte surface was investigated by varying the partial molar volume of divalent ions. To assess the viability of using Poisson–Boltzmann (PB) calculations for determining divalent ion concentrations at DNA surfaces, Monte Carlo (MC) calculations were compared with PB calculations using different models of the dielectric continuum. It was determined that, while standard PB calculations of divalent ion surface densities are about 25–30% below those predicted by MC techniques, and somewhat larger than errors previously determined for monovalent ions, errors due to the use of the mean‐field approximation of PB theory are smaller than those arising from common assumptions regarding the dielectric continuum. © 1999 John Wiley & Sons, Inc. Biopoly 49: 575–590, 1999