Related Experiment Video
Updated: Jan 21, 2026

Collection and Extraction of Saliva DNA for Next Generation Sequencing
Published on: August 27, 2014
Effects of Sequence Changes on the Torsion Elastic Constant and Persistence Length of DNA. Applications of the
1Department of Chemistry , University of Washington , Box 351700, Seattle , Washington 98195 , United States.
Abstract:
Previous experimental studies of the effects of changes in sequence on the elastic constants and other properties of DNAs are analyzed using the recently parametrized two-state cooperative transition model. With appropriate assumptions regarding the relative preference of particular subsequences for the b and a states, the model gives an approximately quantitative account of the surprisingly large observed effects of replacing 25 bp of natural sequence near the middle of an ∼1100 bp DNA by 16 bp of alternating (CG)8 sequence on the fraction f of base-pairs in the b-state and on the torsion elastic constant. This demonstrates the effect of the strong cooperativity of the transition to significantly influence the state of the DNA over surprisingly large domains of the flanking DNA. With appropriate assumptions regarding the disposition of nonrelaxing (permanent) and slowly relaxing bends between the a and b states, the two-state model resolves the discrepancy between experimental estimates of the magnitude of the nonrelaxing bends obtained from studies of synthetic straight and natural DNA sequences by cryo-electron microscopy on the one hand and by j-factors inferred from the kinetics of ligase cyclization of small ∼200 bp circular DNAs on the other. Approximately quantitative agreement with the experiments is again obtained.
Related Concept Videos
Torsion of Noncircular Members
Torsional Pendulum
As long as the rigid body's angular displacement is small, its oscillation can be modeled as a linear angular oscillation. The amplitude of the oscillation is an angle. The role of mass is played...
Bending and Torsional Moments
The reaction developed in a structural element when subjected to an external force causes the element to bend. When a structural element bends upwards, it creates compressive normal forces on the top and tensile normal forces on the bottom, resulting in a couple that determines the bending...
DNA Topoisomerases
Types and Mechanism of action
Topoisomerases are divided into two main types. ...
Constant Pressure Calorimetry
Constant Volume Calorimetry

