Related Experiment Videos
The interactions between the fluorescent dye thiazole orange and DNA
J Nygren1, N Svanvik, M Kubista
1Department of Biochemistry and Biophysics Lundberg Institute, Chalmers University of Technology, Göteborg, Sweden.
Biopolymers
|June 5, 1998
Summary
Thiazole orange (TO) preferentially binds to double-stranded DNA, exhibiting significantly higher affinity than to single-stranded nucleic acids. Its fluorescence properties change dramatically upon binding, influenced by nucleic acid structure and temperature.
Area of Science:
- Biophysical Chemistry
- Molecular Biology
- Fluorescent Probes
Background:
- Thiazole orange (TO) is a fluorescent dye used to detect nucleic acids.
- Understanding its binding interactions is crucial for accurate molecular analysis.
Purpose of the Study:
- To characterize the binding affinity and fluorescence properties of thiazole orange (TO) with various nucleic acid structures.
- To elucidate the influence of nucleic acid secondary structure and environmental factors on TO-nucleic acid interactions.
Main Methods:
- Spectroscopic analysis to determine binding constants (K) and fluorescence quantum yields.
- Investigating TO interactions with double-stranded DNA (dsDNA), single-stranded polypurines, and single-stranded polypyrimidines.
- Assessing the effect of temperature on TO fluorescence.
Main Results:
- TO exhibits highest affinity for dsDNA (log K ≈ 5.5), with weaker binding to single-stranded polypurines and significantly lower affinity for polypyrimidines.
- Binding modes vary (monomer/dimer) depending on the nucleic acid type.
- Fluorescence quantum yield of TO increases substantially upon binding, ranging from 0.01 to 0.4, and is temperature-dependent.
Conclusions:
- Thiazole orange's binding affinity and fluorescence are highly dependent on nucleic acid structure.
- The dye's spectral properties are modulated by its binding state and the local environment.
- These findings are critical for optimizing TO as a fluorescent probe in molecular biology applications.