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Updated: May 22, 2026
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High Sensitivity Measurement of Transcription Factor-DNA Binding Affinities by Competitive Titration Using Fluorescence Microscopy
Published on: February 7, 2019
Fluorometric study of fluoxetine DNA binding
Soheila Kashanian1, Sanaz Javanmardi, Arash Chitsazan
1Faculty of Chemistry, Sensor and Biosensor Research Center and Nanoscience and Nanotechnology Research Center, Razi University, P.O. Box: 67149, Kermanshah, Islamic Republic of Iran. kashanian_s@yahoo.com
Summary
Fluoxetine (FLX) interacts with calf thymus DNA (ctDNA) through non-intercalative binding, primarily driven by entropy. This study clarifies the antidepressant
Area of Science:
- Biochemistry
- Molecular Biology
- Pharmacology
Background:
- Fluoxetine (FLX) is a widely used selective serotonin reuptake inhibitor (SSRI) for depression treatment.
- Understanding drug-DNA interactions is crucial for drug development and safety assessments.
Purpose of the Study:
- To investigate the binding interaction between Fluoxetine (FLX) and calf thymus DNA (ctDNA).
- To elucidate the binding mode, thermodynamics, and binding constants of FLX with DNA under physiological conditions.
Main Methods:
- Fluorescence spectroscopy was employed using methylene blue (MB) as a probe.
- Quenching studies with iodide ions (I-), ionic strength variations (NaCl), and competitive binding assays with MB were performed.
- Thermodynamic parameters were calculated using the Van't Hoff equation.
Main Results:
- A strong fluorescence quenching of DNA by FLX was observed, indicating interaction.
- Binding constants (K(f)) and binding sites (n) were determined at different temperatures (281, 310, 318K).
- Results suggest FLX binds to ctDNA via an outside, non-intercalative mechanism, driven by entropy.
Conclusions:
- Fluoxetine (FLX) interacts with calf thymus DNA (ctDNA) through non-intercalative binding.
- The interaction is entropically driven, suggesting a favorable conformational change upon binding.
- Further studies with specific polynucleotides (poly A-T, poly C-G) were conducted to understand binding site specificity.
