Related Experiment Video
Updated: Aug 16, 2026

Stretching Short Sequences of DNA with Constant Force Axial Optical Tweezers
Published on: October 13, 2011
Osmotic pressure of DNA solutions and effective diameter of the double helix
E G Yarmola1, M I Zarudnaya, Lazurkin YuS
1Institute of Molecular Genetics, USSR Academy of Sciences, Moscow.
Abstract:
A simple osmometer with nuclear filters (polymer films with pores of a preset diameter) were used to measure the osmotic pressure of Col E1 plasmid DNA solutions in the concentration range of 1-4 mg/ml DNA. Linear and open circular DNA forms proved to have the same osmotic pressure within the experimental accuracy. The results of the measurements were used for calculating the second virial coefficient A2 of the solution of DNA segments and the effective chain diameter d eff in the ionic strength range of 10(-2)-0.1 M. As the ionic strength is lowered from 0.1 to 10(-2) M the effective diameter of DNA increases from 80 to 220 A. The results are in rather good agreement with theory and with other experimental data.
Related Concept Videos
Osmosis and Osmotic Pressure of Solutions
DNA as a Genetic Template
Chromatin Packaging
The chromatin
In combination with specialized DNA binding protein called Histones, the DNA double helix forms a compact DNA: protein complex called chromatin. The chromatin itself is further compacted into higher-order structures.
Single-Strand DNA Binding Proteins
Chromatin Packaging
Osmotic Pressure

