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Published on: February 7, 2019
Binding studies of pyriproxyfen to DNA by multispectroscopic atomic force microscopy and molecular modeling methods
Farhad Ahmadi1, Nasibeh Jamali, Rostam Moradian
1Department of Medicinal Chemistry, Faculty of Pharmacy, Kermanshah University of Medical Sciences, Kermanshah, Iran.
DNA and Cell Biology
|August 25, 2011
Summary
Pyriproxyfen (PYR) insecticide interacts with Calf-Thymus-DNA (CT-DNA) through intercalation and groove binding. This interaction is base sequence dependent, favoring AT sequences, and involves both base pairs and the DNA backbone.
Area of Science:
- Biochemistry
- Molecular Biology
- Environmental Science
Background:
- Pesticides can interact with biological macromolecules like DNA.
- Understanding insecticide-DNA interactions is crucial for assessing environmental and health impacts.
- Pyriproxyfen (PYR) is a widely used insecticide whose interaction with DNA requires detailed investigation.
Purpose of the Study:
- To elucidate the interaction mechanisms between pyriproxyfen (PYR) and Calf-Thymus-DNA (CT-DNA).
- To determine the binding affinity, thermodynamic parameters, and structural effects of PYR on DNA.
- To investigate the base sequence dependency of PYR-DNA interactions using experimental and computational methods.
Main Methods:
- Multispectroscopic techniques including UV-Vis absorbance, Fourier transform infrared (FTIR), and circular dichroism (CD) spectroscopy.
- Fluorimetric studies to analyze fluorescence enhancement.
- Atomic force microscopy (AFM) for structural visualization.
- Molecular modeling using hybrid quantum mechanical/molecular mechanics (QM/MM) calculations at the ONIOM 2(B3LYP/6-31++G(d,p): Universal Force Field (UFF)) level.
Main Results:
- A binding constant of 2.8×10(4) was determined for PYR-ds-DNA interaction.
- Thermodynamic analysis indicated spontaneous interaction (ΔG = -82.46 KJ mol⁻¹), driven by enthalpy (ΔH = -53.82 kJ mol⁻¹).
- FTIR revealed PYR interacts with G-C and A-T base pairs and the PO(2) backbone group. QM/MM calculations showed sequence-dependent interaction, favoring AT-rich regions.
Conclusions:
- Pyriproxyfen (PYR) interacts with double-strand DNA (ds-DNA) via a combination of intercalation and outside groove binding.
- The interaction is thermodynamically favorable and influenced by DNA base sequence, with a preference for AT sequences.
- Multispectroscopic and computational data provide a comprehensive understanding of PYR-DNA binding, informing risk assessment.
