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Chlorobenzylidine-herring sperm DNA interaction: binding mode and thermodynamic studies
Wenying Zhong1, Jun-Sheng Yu, Yingqiu Liang
1State Key Laboratory of Coordination Chemistry, Laboratory of Mesoscopic Materials Science, Nanjing University, 210093, Nanjing, People's Republic of China.
Summary
Chlorobenzilidine intercalates into herring sperm DNA, confirmed by spectral changes and thermodynamic data. This interaction is exothermic, indicating a stable binding mechanism between the compound and DNA.
Area of Science:
- Biochemistry
- Molecular Biology
- Chemical Biology
Background:
- Understanding drug-DNA interactions is crucial for developing novel therapeutic agents.
- Herring sperm DNA is a widely used model system for studying DNA-binding compounds.
Purpose of the Study:
- To investigate the binding mechanism of chlorobenzilidine with herring sperm DNA.
- To characterize the thermodynamic parameters of this interaction.
Main Methods:
- Absorption and fluorescence spectroscopy.
- DNA melting temperature experiments.
- Differential scanning calorimetry (DSC).
Main Results:
- Chlorobenzilidine binding induced hypochromism and red shift in absorption spectra.
- Fluorescence quenching and increased polarization were observed upon binding.
- DNA melting temperature increased, supporting intercalation.
- DSC revealed an exothermic interaction with a van't Hoff enthalpy of -30.6 kJ mol(-1).
- Thermodynamic parameters: ΔG° = -28.5 kJ mol⁻¹, ΔS° = -7.1 J mol⁻¹ K⁻¹.
Conclusions:
- Spectral and thermodynamic data strongly support the intercalation of chlorobenzilidine into herring sperm DNA.
- The binding process is exothermic and thermodynamically favorable.
- Chlorobenzilidine exhibits a binding constant of 3.2 x 10⁴ M⁻¹ with a binding site size of six base pairs.