Premium
Influence of temperature and ionic strength on the low‐frequency dielectric dispersion of DNA solutions
Author(s) -
Tung Ming Sung,
Molinari Robert J.,
Cole Robert H.,
Gibbs Julian H.
Publication year - 1977
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.1977.360161207
Subject(s) - chemistry , dielectric , counterion , relaxation (psychology) , ionic bonding , polarization (electrochemistry) , low frequency , ionic strength , thermodynamics , analytical chemistry (journal) , aqueous solution , ion , materials science , chromatography , organic chemistry , social psychology , psychology , physics , optoelectronics , astronomy
Abstract The dielectric properties of DNA solutions at low frequencies (5 Hz to 2 kHz) have been measured by means of a four‐terminal bridge method utilized to minimize electrode polarization errors. At 24°C native salt‐free DNA has a very large specific dielectric increment, Δε/ c = 9.8 × 10 6 l/mol and a very low frequency relaxation centered at 18 Hz. Both the dielectric increment and the relaxation time are greatly decreased by partial heat denaturation at temperatures above 60°C or by addition of salt, the effects being much larger for divalent anions. These results are shown to be in qualitative agreement with theoretical treatments of counterion fluctuation polarization by McTague and Gibbs for the equilibrium case and by Mandel for relaxation. The ratio of the relaxation time for the low‐frequency process to that previously observed at much higher frequencies suggests that these relaxations result from counterion fluctuations along the longitudinal and transverse axes of the molecule, respectively.