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The dielectric constant of a folded protein
Author(s) -
Gilson Michael K.,
Honig Barry H.
Publication year - 1986
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/bip.360251106
Subject(s) - dielectric , chemistry , dipole , isotropy , polar , structure factor , constant (computer programming) , computational chemistry , thermodynamics , condensed matter physics , statistical physics , molecular physics , physics , crystallography , quantum mechanics , organic chemistry , computer science , programming language
The goal of this paper is to obtain a theoretical estimate of the dielectric constant of a folded protein. To this end, we develop a form of the Kirkwood–Fröhlich dielectric theory that applies to polar solids and folded proteins. The resulting theory incorporates a factor expressing the degree to which dipolar groups are constrained within the material's structure, as well as a generalized form of Kirkwood's correlation factor. The theory is applied to a hypothetical isotropic protein composed of randomly oriented α‐helices and having a number density of dipolar groups equal to that found in actual proteins. The factor of constraint and the generalized dipole correlation factor are calculated using normal mode analysis. Temperature factors are also computed by normal mode analysis and are in reasonable agreement with those found experimentally. The computed dielectric constant is low; the best estimate is that it falls between 2.5 and 4.