Na Li,Xing Hu,Junhui Pan,Ying Zhang,Deming Gong,Guowen Zhang
4–Octylphenol is an endocrine disruptor , belonging to environmental estrogens. It can be enriched in the human body through the food chain and may harm human health. Herein, we used a variety of spectroscopic techniques, molecular docking, and gel electrophoresis to study the interaction of 4–octylphenol and ctDNA . It was found that the mechanism of ctDNA quenching the endogenous fluorescence of 4–octylphenol was static quenching, and formed a complex. The negative enthalpy change (Δ H °), entropy change (Δ S °) and Gibbs free energy (Δ G °) have shown that 4–octylphenol and ctDNA spontaneously bind together under the action of hydrogen bonds and van der Waal's force . Viscosity, melting temperature and iodide quenching experiments showed that 4–octylphenol acted on the groove of ctDNA. Insignificant change in circular dichromism spectra further confirmed this binding mode. The binding sites and groups for 4–octylphenol and ctDNA interaction were identified by molecular docking. Gel electrophoresis found that 4–octylphenol at high concentrations caused DNA cleavage. Above findings may lay a theoretical foundation for understanding the toxicity mechanism of 4–octylphenol.
Xu Li,Yue Yuan,Yuting Wang,Fengming Zhang,Rui Zhao,Di Shao,Shuyun Bi
The investigation on the binding interaction mechanism of florfenicol with DNA in vitro was reported via multi-spectroscopy measurements and molecular docking approach in the present work. The static fluorescence quenching process accompanied with non-radiation energy transfer between florfenicol and DNA was confirmed by Stern-Volmer analysis, lifetime measurement and fluorescence resonance energy transfer study. Florfenicol was the A-T rich minor groove binding agent of DNA. Various experiments including site marker competitive experiments, viscosity measurements, helix melting studies, ionic strength measurements, thermal denaturation experiments, circular dichroism (CD) spectra measurements and UV–vis spectra characteristics were carried out to disclose the interaction mode. In addition, molecular docking stimulated appropriate binding orientation to further prove above experimental results. The binding constants were 6.92 × 10 3 , 6.21 × 10 3 and 5.61 × 10 3 M −1 at 291, 301 and 311 K respectively and the binding distance r 0 was 5.30 nm. Thermodynamic parameters, such as Δ H Ө =−7.90 kJ mol −1 and Δ S Ө = 46.39 J mol −1 K −1 , showed that electrostatic attraction was the key force in the binding.
In this work, a dumbbell-shaped bi-acetylferrocene ethylenediamine complex, (AFc) 2 -en (AFc = acetylferrocene, en = ethylenediamine) was synthesized and its interaction with double-stranded DNA (dsDNA) was comprehensively studied by electrochemical methods on a gold electrode. The experimental results reveal that the highly electroactive (AFc) 2 -en complex can interact with dsDNA via a specific bis-groove binding mode. The binding constant and binding site size between the two species were determined to be 3.7 × 10 5 L mol −1 and 4.2, respectively. The surface-based studies further show that (AFc) 2 -en presents the stronger electrochemical response on dsDNA modified electrode than on the single-stranded DNA (ssDNA) modified electrode, suggesting that the complex can well distinguish dsDNA from ssDNA. Based on this characteristic, the bi-acetylferrocene complex was utilized as an electrochemical hybridization indicator in a DNA biosensor for the detection of oligonucleotides from CaMV35S promoter gene. The specificity experiments indicate that the biosensor can well discriminate the complementary sequence from the base-mismatched and the non-complementary sequences. The complementary target sequence can be quantified over a wide range from 1.0 × 10 −14 mol L −1 to 1.0 × 10 −6 mol L −1 with a detection limit of 2.0 × 10 −15 mol L −1 .
危险品化学品经营许可证（带存储）