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Formation of a stable triplex from a single DNA strand
1Department of Chemistry and Biochemistry, University of California, Los Angeles 90024.
Nature
|June 28, 1990
Summary
Homopurine.homopyrimidine DNA sequences form stable triple-stranded structures. A novel 28-base DNA oligomer was designed to create a well-defined intramolecular triplex, demonstrating potential for in vivo applications.
Area of Science:
- Molecular Biology
- Biochemistry
- Structural Biology
Background:
- Homopurine.homopyrimidine DNA sequences readily form triple-stranded structures.
- DNA triplexes have potential applications as antisense inhibitors and roles in gene regulation.
- Previous studies confirmed Hoogsteen base pairing and cytosine protonation in DNA triplexes.
Purpose of the Study:
- To design and synthesize a DNA oligomer capable of forming a well-defined intramolecular triplex.
- To provide a model for in vivo DNA triplex structures.
- To investigate the pH-dependent stability of the designed triplex.
Main Methods:
- Design and synthesis of a 28-base DNA oligomer.
- Nuclear Magnetic Resonance (NMR) spectroscopy to analyze triplex formation.
- pH-dependent structural analysis of the DNA oligomer.
Main Results:
- The synthesized 28-base oligomer formed an intramolecular triplex at pH 5.5.
- Significant triplex formation was observed even at neutral pH (8.0).
- The triplex structure incorporates both T.A.T and C+.G.C triplets.
Conclusions:
- The designed DNA oligomer successfully folds into a stable intramolecular triplex.
- This triplex serves as a valuable model for studying in vivo DNA triplex structures.
- The triplex exhibits stability across a relevant physiological pH range.