Development of electrochemical telomerase assay aiming for cancer diagnosis in the early stage

端粒DNA是存在于人类染色体末端的TTAGGG的重复序列，已知其形成独特的四链体结构。人工配体能够与这种结构的DNA结合并稳定其结构，从新型抗癌药物的角度来看是重要的。我们发现二茂铁基萘二酰亚胺（FND）能与四链DNA结合，并使其稳定。此外，我们发现FND可以用于电化学端粒酶检测。这是由于电化学检测FND在端粒酶延伸的端粒DNA上的选择性浓度。在本研究中，我们做了一系列的实验，以获得详细的信息，其结合方式的四链DNA。结果表明，该配体可以通过与四链体DNA的三个G-四链体平面的上部或底部的堆积作用与四链体DNA结合。我们还合成了一系列的FND衍生物，并评价了它们与四链DNA的结合行为。它们的结合亲和力根据它们在二茂铁和萘二酰亚胺部分之间的连接链而变化。这些实验是在钾离子存在下进行的电化学实验，其中四链体结构没有明确确定（最近，我们的实验结果和以前的论文表明其明确的混合型结构）。我们在钠离子存在下进行了结合实验，其中四链体结构被明确地确定为篮式结构，并且在钾离子的情况下表现出类似的结合行为。为了提高四链体DNA的结合亲和力，合成了二茂铁基苝酰亚胺，并研究了其与四链体DNA的结合。这些结果为开发适合于电化学端粒酶检测的新型四链体选择性配体提供了依据。

Telomere DNA, which is repeated sequence of TTAGGG existing in the termini of a human chromosome, is known to form an unique tetraplex structure. Artificial ligand, which can bind to such structural DNA and stabilized its structure, is an important in the view point of new anticancer drug. We found that ferrocenylnaphthalene diimide (FND) could bind to tetraplex DNA and stabilized its complex. Furthermore, we reveled that FND could be used for an electrochemical telomerase assay. This drove from the electrochemical detection of the selective concentration of FND on the telomere DNA extended by telomerase. In this study, we did the series of the experiments to obtain the detailed information of its binding manner for tetraplex DNA. The result suggested that this ligand could bind the tetraplex DNA through the stacking interaction with the upper or bottom of its three G-quartet planes. We also synthesized the series of the FND derivatives and evaluated their binding behaviors with tetraplex DNA. Their binding affinities were varied depending on their linker chains between the ferrocene and naphthalene diimide parts. These experiments were carried out in the presence of potassium ion as electrochemical experiment, where tetraplex structure was not determined unambiguously (Most recently, our experimental result and the previously papers suggested its unambiguous structure of hybrid type). We did the binding experiments in the presence of sodium ion, where tetraplex structure was determined as basket-type structure unambiguously and showed the similar binding behaviors in the case of potassium ion. To improve the binding affinity for tetraplex DNA, ferrocenylperylene diimide was newly synthesized and was studied on the binding with tetraplex DNA. These results obtained here should provide the information in the development of new tetraplex-selective ligand suitable for electrochemical telomerase assay.