Bourassa P, Tajmir-Riahi H A
Department of Chemistry-Biochemistry-Physics, University of Québec at Trois-Rivières, C.P. 500, Trois-Rivières, Québec G9A 5H7, Canada.
Department of Chemistry-Biochemistry-Physics, University of Québec at Trois-Rivières, C.P. 500, Trois-Rivières, Québec G9A 5H7, Canada.
Int J Biol Macromol. 2015 Mar;74:337-42. doi: 10.1016/j.ijbiomac.2014.12.007. Epub 2014 Dec 30.
We located multiple binding sites for folic acid on DNA and tRNA at physiological conditions, using FTIR, CD, fluorescence spectroscopic methods and molecular modeling. Structural analysis revealed that folic acid binds DNA and tRNA at multiple sites via hydrophilic, hydrophobic and H-bonding contacts with overall binding constants of Kfolic acid-DNA=1.1 (±0.3)×10(4) M(-1) and Kfolic acid-tRNA=6.4 (±0.5)×10(3) M(-1). Molecular modeling showed the participation of several nucleobases in folic acid complexes with DNA and tRNA, stabilized by H-bonding network. Two types of complexes were located for folic acid-tRNA adducts, one at the major groove and the other with TΨC loop, while acid binding occurs at major and minor grooves of DNA duplex. Folic acid complexation induced more alterations of DNA structure than tRNA.
我们使用傅里叶变换红外光谱（FTIR）、圆二色光谱（CD）、荧光光谱方法和分子建模，在生理条件下确定了叶酸在DNA和tRNA上的多个结合位点。结构分析表明，叶酸通过亲水、疏水和氢键接触在多个位点与DNA和tRNA结合，叶酸与DNA的总体结合常数为K叶酸-DNA = 1.1（±0.3）×10⁴ M⁻¹，叶酸与tRNA的总体结合常数为K叶酸-tRNA = 6.4（±0.5）×10³ M⁻¹。分子建模显示，几种核碱基参与了叶酸与DNA和tRNA的复合物形成，并通过氢键网络得以稳定。叶酸与tRNA加合物定位出两种类型的复合物，一种位于大沟，另一种与TΨC环相关，而叶酸与DNA双链体的结合发生在大沟和小沟。叶酸络合对DNA结构的改变比tRNA更多。
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