Boal Amie K, Barton Jacqueline K
Division of Chemistry and Chemical Engineering, California Institute of Technology, Pasadena, California 91125, USA.
Bioconjug Chem. 2005 Mar-Apr;16(2):312-21. doi: 10.1021/bc0497362.
Electrochemical DNA-based sensors that exploit the inherent sensitivity of DNA-mediated charge transport (CT) to base pair stacking perturbations are capable of detecting base pair mismatches and some common base damage products. Here, using DNA-modified gold electrodes, monitoring the electrocatalytic reduction of DNA-bound methylene blue, we examine a wide range of base analogues and DNA damage products. Among those detected are base damage products O4-methyl-thymine, O6-methyl-guanine, 8-oxo-guanine, and 5-hydroxy-cytosine, as well as a therapeutic base, nebularine. The efficiency of DNA-mediated CT is found not to depend on the thermodynamic stability of the helix. However, general trends in how base modifications affect CT efficiency are apparent. Modifications to the hydrogen bonding interface in Watson-Crick base pairs yields a substantial loss in CT efficiency, as does added steric bulk. Base structure modifications that may induce base conformational changes also appear to attenuate CT in DNA as do those that bury hydrophilic groups within the DNA helix. Addition and subtraction of methyl groups that do not disrupt hydrogen bonding interactions do not have a large effect on CT efficiency. This sensitive detection methodology based upon DNA-mediated CT may have utility in diagnostic applications and implicates DNA-mediated CT as a possible damage detection mechanism for DNA repair enzymes.
利用DNA介导的电荷传输（CT）对碱基对堆积扰动的固有敏感性的基于电化学DNA的传感器，能够检测碱基对错配和一些常见的碱基损伤产物。在此，我们使用DNA修饰的金电极，监测与DNA结合的亚甲基蓝的电催化还原，研究了多种碱基类似物和DNA损伤产物。检测到的物质包括碱基损伤产物O4-甲基胸腺嘧啶、O6-甲基鸟嘌呤、8-氧代鸟嘌呤和5-羟基胞嘧啶，以及一种治疗性碱基，喷司他丁。发现DNA介导的CT效率并不取决于螺旋的热力学稳定性。然而，碱基修饰如何影响CT效率的一般趋势是明显的。对沃森-克里克碱基对中氢键界面的修饰会导致CT效率大幅损失，增加空间位阻也是如此。可能诱导碱基构象变化的碱基结构修饰，以及将亲水基团埋入DNA螺旋内的修饰，似乎也会减弱DNA中的CT。不破坏氢键相互作用的甲基的添加和去除对CT效率影响不大。这种基于DNA介导的CT的灵敏检测方法可能在诊断应用中有实用价值，并暗示DNA介导的CT可能是DNA修复酶的一种损伤检测机制。
