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The contribution of proton fluctuation to dielectric relaxation in protein solutions
Author(s) -
South G. P.,
Grant E. H.
Publication year - 1973
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.1973.360120902
Subject(s) - chemistry , dipole , globular protein , polarization (electrochemistry) , proton , macromolecule , relaxation (psychology) , dielectric , dispersion (optics) , electric field , dispersion relation , permittivity , nuclear magnetic resonance , chemical physics , condensed matter physics , molecular physics , physics , quantum mechanics , crystallography , psychology , social psychology , biochemistry , organic chemistry
Equations are derived which account for the effect of an applied electric field on the fluctuation of protons associated with a macromolecule. The contribution of this proton polarization to the complex permittivity of the macromolecules is evaluated in terms of its effect on both the dispersion due to proton fluctuation and the dispersion caused by dipolar rotation. An expression for the fluctuation correlation time τ i δ is derived in terms of the mean lifetimes of the ionised and unionised state τ0 and τ+. If τ i δ is very much less than the dipolar correlation time τ i , the fluctuation dispersion will occur at much higher frequencies than the dispersion due to orientation polarization; hence the dispersions will be well separated. If τ i δ » τ i the two regions would overlap and would be indistinguishable as separate entities. At present insufficient data are available to test rigorously these conclusions but the potentialities of the theory in relation to small globular proteins is shown.