Related Experiment Videos
Polymorphism and disorder of poly(dA).poly(dT) in fibers
A Lamiri1, G Albiser, S Premilat
1Laboratoire de Biophysique Moléculaire, UMR 7565 Université H. Poincaré-Nancy 1, Faculté des Sciences, Vandoeuvre les Nancy, France.
Biochemical and Biophysical Research Communications
|January 27, 1999
Summary
Poly(dA).poly(dT) fibers show significant disorder with changing relative humidity, impacting fiber length without altering conformation. An amorphous component influences length changes, not structural transitions.
Area of Science:
- Biophysics
- Molecular Biology
- Polymer Science
Background:
- Poly(dA).poly(dT) is a synthetic DNA polymer with potential applications in nanotechnology and gene therapy.
- Understanding its structural behavior under varying environmental conditions is crucial for its application.
- Previous studies have indicated complex structural dynamics in nucleic acid fibers.
Purpose of the Study:
- To investigate the relationship between fiber length and structural disorder in poly(dA).poly(dT) under varying relative humidity.
- To elucidate the role of conformational changes and amorphous components in poly(dA).poly(dT) fiber length variations.
- To analyze the impact of temperature on the structural transitions and associated length changes.
Main Methods:
- X-ray diffraction patterns were used to analyze the structure of poly(dA).poly(dT) fibers.
- Fiber length measurements were correlated with relative humidity and temperature.
- Structural characterization was performed across a range of relative humidity levels.
Main Results:
- A lack of proportionality between fiber length and interbase axial distance indicates high disorder in poly(dA).poly(dT) fibers with changing relative humidity.
- Increased fiber length did not correlate with conformational changes; the B' structure was favored at higher relative humidity.
- An unusual minimum in fiber length around 65% relative humidity was observed and attributed to an amorphous component.
- A B'(alpha)-B* transition above 30°C caused a significant decrease in fiber length, independent of helical rise per base pair, due to the amorphous part.
Conclusions:
- The structural behavior of poly(dA).poly(dT) fibers is significantly influenced by relative humidity and temperature.
- An amorphous component, rather than conformational transitions, is primarily responsible for the observed length variations.
- These findings highlight the importance of considering non-helical components in understanding DNA fiber mechanics.