Electrostatic interactions in protein solution—a comparison between poisson–boltzmann and Monte Carlo calculations
✍ Scribed by M. Fushiki; B. Svensson; Bo Jönsson; C. E. Woodward
- Publisher
- Wiley (John Wiley & Sons)
- Year
- 1991
- Tongue
- English
- Weight
- 766 KB
- Volume
- 31
- Category
- Article
- ISSN
- 0006-3525
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✦ Synopsis
The accuracy of the Poisson-Boltzmann ( P B ) approximation and its linearized version is investigated by comparison to results obtained from Monte Carlo simulations. The dependence of the calcium binding constant of the protein calbindin as a function of salt concentration and mutation is used as a test case. The protein is modeled as a collection of charged and neutral spheres immersed in the electrolyte solution. The P B equation is solved using a finite difference technique on a grid in a spherical polar coordinate system, which is the preferred choice for a globular protein like calbindin. Both MC and P B give quantitative agreement with experimental results. The linearized P B equation is almost as accurate, but it becomes less reliable in systems with divalent ions. However, the linearized P B equation fails to describe the concentration profiles for cations and anions outside the protein even in a 1 : 1 salt solution.