The structural change of individual giant double-stranded T4 DNA (165.6 kilobase pairs) molecules as a function of salt concentration was investigated by single molecular observation with fluorescence microscopy in a wide range of concentration of NaCl, 1 x 10(-6)-3 M. The measured long-axis length was transformed into a persistence length and subjected to a power-law analysis, which showed that the electrostatic contribution to the persistence length is inversely proportional to the square root of the salt concentration; i.e., it has a linear dependence on the screening length. This is interpreted as the behavior of a flexible chain with electrostatic excluded-volume interactions. Although double-stranded DNA is locally stiff, it displays flexibility when the contour length is much longer than the persistence length, as is the case for T4 DNA.
Bibliographical noteThe information about affiliations in this record was updated in December 2015.
The record was previously connected to the following departments: Theoretical Chemistry (S) (011001039)
Subject classification (UKÄ)
- Theoretical Chemistry