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Updated: Feb 7, 2026
05:37
Single-Molecule Fluorescence Visualization of DNA Polymerase Dynamics at G-Quadruplexes
Published on: April 4, 2025
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DNA influence on norfloxacin fluorescence.
Elena Perianu1, Ileana Rau1, Loredana Elena Vijan2
1Faculty of Applied Chemistry and Materials Science, University POLITEHNICA of Bucharest, Polizu Street No 1, RO-011061 Bucharest, Romania.
Summary
Norfloxacin, a quinolone antibiotic, intercalates into salmon sperm DNA, altering its structure and fluorescence. This interaction is a diffusion-limited, pH-independent process involving both dynamic and static quenching mechanisms.
Area of Science:
- Biochemistry
- Molecular Biology
- Pharmacology
Background:
- Norfloxacin is a widely used quinolone antibiotic.
- Understanding drug-DNA interactions is crucial for pharmacology and toxicology.
- Fluorescence spectroscopy is a sensitive tool for studying molecular interactions.
Purpose of the Study:
- To investigate the interaction between norfloxacin and salmon sperm DNA.
- To characterize the binding mode and fluorescence quenching mechanism.
- To assess the influence of pH on the norfloxacin-DNA interaction.
Main Methods:
- Fluorescence spectroscopy at room temperature and varying pH (acid, alkaline, neutral).
- Viscosity measurements to detect DNA intercalation.
- Analysis using Stern-Volmer plots and modified equations (dynamic and static quenching).
- Application of finite sink approximation and ground state complex models.
Main Results:
- Norfloxacin intercalates into DNA base pairs, confirmed by spectral changes and increased DNA viscosity.
- Positive deviation in Stern-Volmer plots indicates complex binding.
- Fluorescence quenching is diffusion-limited and pH-independent.
- Both dynamic and static quenching contribute to the observed fluorescence quenching.
Conclusions:
- Norfloxacin binds to salmon sperm DNA via intercalation.
- The fluorescence quenching mechanism is a combination of dynamic and static processes.
- pH does not significantly affect the quenching mechanism, suggesting robust interaction.
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