In this paper, the binding characteristics of aflatoxin B1 (AFB1) with the herring sperm deoxyribonucleic acid (DNA) in vitro were investigated through different analytical methods. The ultraviolet-visible spectroscopy (UV-vis), fluorescence, and circular dichroism (CD) spectra results showed that a new AFB1-DNA complex was formed. All the results suggested that AFB1 interacted with free DNA in vitro in an intercalating binding mode. The results of the DNA melting experiments also showed that the melting temperature of DNA increased by about 12.1 °C due to the addition of AFB1, which was supposed to be closely related to the intercalation of AFB1 into DNA. The agar gel electrophoresis experiments further confirmed that the binding mode of AFB1 and free DNA in vitro was indeed intercalation. In addition, the fluorescence quenching induced by adding AFB1 to the ethidium bromide-DNA (EB-DNA) mixture indicated the presence of competitive non-covalent intercalating binding interaction with a competitive binding constant of 5.58 L/mol between AFB1, EB, and DNA. The thermodynamic data demonstrated that the main driving forces of the binding reaction were van der Waals forces and hydrogen bond. The resonance light scattering (RLS) assay results showed that the DNA binding saturation values of AFB1, EB, psoralen (PSO), and angelicin (ANG) were 2.14, 15.59, 0.74, and 0.74, respectively. These results indicated that the DNA binding capacity of AFB1 was weaker than that of EB, but stronger than those of PSO and ANG.

中文翻译：

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黄曲霉毒素B1与游离DNA的体外结合特征。

本文通过不同的分析方法研究了黄曲霉毒素B1（AFB1）与鲱鱼精子脱氧核糖核酸（DNA）的结合特性。紫外-可见光谱（UV-vis），荧光和圆二色性（CD）光谱结果表明形成了新的AFB1-DNA复合物。所有结果表明，AFB1在体外以游离结合模式与游离DNA相互作用。DNA熔解实验的结果还表明，由于添加了AFB1，DNA的熔解温度提高了约12.1°C，这被认为与AFB1插入DNA密切相关。琼脂凝胶电泳实验进一步证实了体外AFB1与游离DNA的结合模式确实是嵌入的。此外，通过向溴化乙锭-DNA（EB-DNA）混合物中添加AFB1诱导的荧光猝灭表明存在竞争性非共价嵌入结合相互作用，AFB1，EB和DNA之间的竞争性结合常数为5.58 L / mol。热力学数据表明，结合反应的主要驱动力是范德华力和氢键。共振光散射（RLS）分析结果表明，AFB1，EB，补骨脂素（PSO）和当归素（ANG）的DNA结合饱和度分别为2.14、15.59、0.74和0.74。这些结果表明，AFB1的DNA结合能力弱于EB，但强于PSO和ANG。