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Implications of a high dielectric constant in proteins

Lund, Mikael LU ; Jönsson, Bo LU and Woodward, Clifford (2007) In Journal of Chemical Physics 126(22).
Abstract
Solvation of protein surface charges plays an important role for the protonation states of titratable surface groups and is routinely incorporated in low dielectric protein models using surface accessible areas. For many-body protein simulations, however, such dielectric boundary methods are rarely tractable and a greater level of simplification is desirable. In this work, we scrutinize how charges on a high dielectric surface are affected by the nonpolar interior core of the protein. A simple dielectric model, which models the interior as a low dielectric sphere, combined with Monte Carlo simulations, shows that for small, hydrophilic proteins the effect of the low dielectric interior is largely negligible and that the protein (and... (More)
Solvation of protein surface charges plays an important role for the protonation states of titratable surface groups and is routinely incorporated in low dielectric protein models using surface accessible areas. For many-body protein simulations, however, such dielectric boundary methods are rarely tractable and a greater level of simplification is desirable. In this work, we scrutinize how charges on a high dielectric surface are affected by the nonpolar interior core of the protein. A simple dielectric model, which models the interior as a low dielectric sphere, combined with Monte Carlo simulations, shows that for small, hydrophilic proteins the effect of the low dielectric interior is largely negligible and that the protein (and solution) can be approximated with a uniform high dielectric constant equal to that of the solvent. This is verified by estimates of titration curves and acidity constants for four different proteins (BPTI, calbindin D-9k, ribonuclease A, and turkey ovomucoid third domain) that all correlate well with experimental data. Furthermore, the high dielectric approximation follows as a natural consequence of the multipole expansion of the potential due to embedded protein charges in the presence of the low dielectric core region. (c) 2007 American Institute of Physics. (Less)
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type
Contribution to journal
publication status
published
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in
Journal of Chemical Physics
volume
126
issue
22
publisher
American Institute of Physics
external identifiers
  • wos:000247247400048
  • scopus:34250702227
ISSN
0021-9606
DOI
10.1063/1.2741543
language
English
LU publication?
yes
id
e448def7-55e1-43ed-92db-b9f9bf7ffd7e (old id 648827)
date added to LUP
2007-12-17 15:18:02
date last changed
2017-01-01 04:30:43
@article{e448def7-55e1-43ed-92db-b9f9bf7ffd7e,
  abstract     = {Solvation of protein surface charges plays an important role for the protonation states of titratable surface groups and is routinely incorporated in low dielectric protein models using surface accessible areas. For many-body protein simulations, however, such dielectric boundary methods are rarely tractable and a greater level of simplification is desirable. In this work, we scrutinize how charges on a high dielectric surface are affected by the nonpolar interior core of the protein. A simple dielectric model, which models the interior as a low dielectric sphere, combined with Monte Carlo simulations, shows that for small, hydrophilic proteins the effect of the low dielectric interior is largely negligible and that the protein (and solution) can be approximated with a uniform high dielectric constant equal to that of the solvent. This is verified by estimates of titration curves and acidity constants for four different proteins (BPTI, calbindin D-9k, ribonuclease A, and turkey ovomucoid third domain) that all correlate well with experimental data. Furthermore, the high dielectric approximation follows as a natural consequence of the multipole expansion of the potential due to embedded protein charges in the presence of the low dielectric core region. (c) 2007 American Institute of Physics.},
  author       = {Lund, Mikael and Jönsson, Bo and Woodward, Clifford},
  issn         = {0021-9606},
  language     = {eng},
  number       = {22},
  publisher    = {American Institute of Physics},
  series       = {Journal of Chemical Physics},
  title        = {Implications of a high dielectric constant in proteins},
  url          = {http://dx.doi.org/10.1063/1.2741543},
  volume       = {126},
  year         = {2007},
}