Related Experiment Video
Updated: Aug 2, 2026
10:32
On-chip Isotachophoresis for Separation of Ions and Purification of Nucleic Acids
Published on: March 2, 2012
Dielectric constant and ionic strength effects on DNA precipitation
S Flock1, R Labarbe, C Houssier
1Laboratoire de Chimie Macromoléculaire et Chimie Physique, Université de Liège, Belgium.
Biophysical Journal
|March 1, 1996
Summary
Zwitterionic compounds like glycine can prevent DNA precipitation caused by spermine. This protective effect is linked to solution dielectric constants, influencing DNA-ion interactions and precipitation.
Area of Science:
- Biochemistry
- Molecular Biology
- Physical Chemistry
Background:
- DNA precipitation is a crucial process in molecular biology.
- Polyamines like spermine are known to induce DNA precipitation.
- Understanding factors influencing DNA precipitation is essential for DNA manipulation and storage.
Purpose of the Study:
- To investigate the effect of zwitterionic compounds on spermine-induced DNA precipitation.
- To correlate the protective capacity of zwitterionic compounds with solution properties.
- To explore the mechanisms of DNA-ion interactions and precipitation.
Main Methods:
- Experimental investigation of DNA precipitation in the presence of various zwitterionic compounds and polyamines.
- Measurement of solution dielectric constants.
- Application of counter-ion condensation theory for data analysis.
Main Results:
- Zwitterionic compounds (glycine, beta-alanine, 4-aminobutyric acid, 6-aminocaproic acid) showed an increasing ability to attenuate DNA precipitation.
- The protective effect correlated with an increase in the dielectric constant of the solutions.
- Resolubilization of precipitated DNA was observed with 6-aminocaproic acid at high spermine concentrations and glycine at high spermidine concentrations.
Conclusions:
- Dielectric constant plays a significant role in DNA-ion interactions and precipitation mechanisms.
- Zwitterionic compounds can effectively modulate DNA precipitation by altering solution properties.
- Increased screening effects with higher polyamine concentrations contribute to DNA resolubilization.
Related Concept Videos
01:34DNA Isolation
DNA from cells is required for many biotechnology and research applications, such as molecular cloning. To remove and purify DNA from cells, researchers use various methods of DNA extraction. While the specifics of different protocols may vary, some general concepts underlie the process of DNA extraction.
02:42Aqueous Solutions and Heats of Hydration
Water and other polar molecules are attracted to ions. The electrostatic attraction between an ion and a molecule with a dipole is called an ion-dipole attraction. These attractions play an important role in the dissolution of ionic compounds in water.
When ionic compounds dissolve in water, the ions in the solid separate and disperse uniformly throughout the solution because water molecules surround and solvate the ions, reducing the strong electrostatic forces between them. This process...
When ionic compounds dissolve in water, the ions in the solid separate and disperse uniformly throughout the solution because water molecules surround and solvate the ions, reducing the strong electrostatic forces between them. This process...
01:24DNA Isolation
DNA isolation protocols can be fast and straightforward or complex and time-consuming depending on the type and quality of DNA required for further processing. For example, plasmid DNA extraction is a bit more complicated than genomic DNA extraction because of the need for an appropriate lysis method to separate plasmid DNA from gDNA during isolation. However, for specific applications, such as long-range DNA sequencing that require a good yield of high- quality DNA samples, we need to follow...
01:12Ionic Strength: Overview
The ionic strength of a solution is a quantitative way of expressing the total electrolyte concentration of a solution. This concept was first introduced in 1921 by two American physical chemists, Gilbert N. Lewis and Merle Randall, while describing the activity coefficient of strong electrolytes. During the calculation of ionic strength (I or μ), all the cations and anions are considered. However, the concentration (c) of an ion with a greater charge number (z) has a greater contribution to...
01:19Ionic Strength: Effects on Chemical Equilibria
The addition of an inert ionic compound increases the solubility of a sparingly soluble salt. For example, adding potassium nitrate to a saturated solution of calcium sulfate significantly enhances the solubility of calcium sulfate. Le Châtelier's principle cannot predict this shift in the equilibrium. Instead, this could be explained in terms of changes in the effective concentration of the ions in solution in the presence of added inert salt.
In this solution, the primary cation—the calcium...
In this solution, the primary cation—the calcium...
01:23Theory of Strong Electrolytes
The interionic forces of the strong electrolytes depend on the solvent's dielectric constant, which is the ability of a solvent to store electrical energy, based on its polarizability. and the solution's concentration. In high-dielectric solvents and in dilute solutions, weak electrostatic forces keep ions apart. However, in low-dielectric solvents or concentrated solutions, stronger interionic forces may cause ions to pair up as ionic doublets despite being fully ionized. The theory of strong...