Related Experiment Videos
DNA mesophases induced by spermidine: structural properties and biological implications
1Laboratoire de Physique des Solides, Université Paris Sud, Orsay, France.
Biophysical Journal
|July 1, 1996
Summary
Spermidine addition to DNA fragments forms two distinct phases: a liquid crystalline phase and a columnar hexagonal phase. These DNA aggregates, retaining their B form, may influence DNA
Area of Science:
- Biochemistry
- Materials Science
- Molecular Biology
Background:
- DNA aggregation is influenced by polyamines like spermidine.
- Understanding DNA phase behavior is crucial for its functional properties.
Purpose of the Study:
- To determine the conditions for DNA aggregate formation using spermidine.
- To characterize the phases of spermidine-DNA complexes.
- To compare these phases with previously described DNA mesophases.
Main Methods:
- Utilized 146 base pair DNA fragments.
- Varied spermidine and NaCl concentrations.
- Analyzed DNA aggregate phases and structures.
Main Results:
- Identified two spermidine-DNA complex phases: cholesteric liquid crystalline and columnar hexagonal.
- Cholesteric phase: large helical pitch (31.6–32.6 Å interhelix distance).
- Columnar hexagonal phase: closely packed DNA (29.85 ± 0.05 Å), restricted fluidity.
Conclusions:
- DNA retains its B form in both observed phases.
- These phases exist in equilibrium with dilute isotropic solutions.
- The liquid crystalline nature of spermidine-DNA complexes likely stimulates DNA's functional properties, with phase dictating activity levels.