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Duplex to quadruplex equilibrium of the self-complementary oligonucleotide d(GGGGCCCC)
1Department of Chemistry, University of Nebraska, Lincoln 68588, USA.
Biopolymers
|June 1, 1995
Summary
The deoxyoligonucleotide d(GGGGCCCC) shifts from a duplex to a quadruplex structure as KCl concentration increases. The quadruplex form is favored at physiological salt levels, showing structural plasticity in DNA.
Area of Science:
- Molecular Biology
- Biochemistry
- Structural Biology
Background:
- Deoxyoligonucleotides can adopt various secondary structures.
- The GGGGCCCC sequence is known to form different DNA structures.
Purpose of the Study:
- To investigate the structural transitions of the deoxyoligonucleotide d(GGGGCCCC).
- To determine the influence of salt concentration on DNA structure.
Main Methods:
- 1H and 31P Nuclear Magnetic Resonance (NMR) spectroscopy.
- Gel electrophoresis.
- Salt titration studies.
Main Results:
- At low salt concentrations, d(GGGGCCCC) forms a stable duplex structure.
- Increasing KCl concentration leads to an equilibrium between duplex and quadruplex forms.
- The quadruplex structure becomes dominant at physiological KCl concentrations.
Conclusions:
- The deoxyoligonucleotide d(GGGGCCCC) exhibits salt-dependent structural polymorphism.
- Quadruplex formation is favored under physiological conditions despite fewer hydrogen bonds per strand compared to duplex.