Liu Lingling, Shao Yong, Peng Jian, Liu Hua, Zhang Lihua
Institute of Physical Chemistry, Zhejiang Normal University, Jinhua 321004, Zhejiang, People's Republic of China.
Mol Biosyst. 2013 Oct;9(10):2512-9. doi: 10.1039/c3mb70201d.
Thioflavin T (ThT) has been widely utilized as a fluorescent marker for amyloid fibrils. However, the use of ThT as an efficient reporter for a specific DNA structure still remains in question. Here, we report that the fluorescence intensity of ThT is obviously enhancement in when it binds to ds-DNAs which contain cavity structures such as an abasic site, gap site or mismatch site. Such enhancement in fluorescence cannot be achieved for DNA without these cavity structures. The DNA cavities provide appropriate spaces to accommodate ThT and allow the occurrence of some specific interactions. The stacking interaction of the bound ThT with the cavity context bases is the main driving force for ThT binding to the cavities. This interaction restricts the excited state's rapid torsional rotation around the single C-C bond between the benzothiazole and dimethylaminobenzene moieties and thus results in a decreased population of the nonradiative twisted internal charge-transfer (TICT) state. It is impossible for this stacking interaction to occur in DNA without these cavities. This property can be used to recognize DNA cavities with high selectivity and sensitivity. We expect that the ability of ThT to target these DNA structures has the potential to be developed into practical and functional biomaterials for DNA sensors or devices.
硫黄素T（ThT）已被广泛用作淀粉样纤维的荧光标记物。然而，将ThT用作特定DNA结构的有效报告分子仍存在疑问。在此，我们报告当ThT与含有诸如无碱基位点、缺口位点或错配位点等空腔结构的双链DNA结合时，其荧光强度会明显增强。对于没有这些空腔结构的DNA，无法实现这种荧光增强。DNA空腔提供了容纳ThT的合适空间，并允许发生一些特定的相互作用。结合的ThT与空腔周围碱基的堆积相互作用是ThT与空腔结合的主要驱动力。这种相互作用限制了激发态围绕苯并噻唑和二甲基氨基苯部分之间的单个C-C键的快速扭转旋转，从而导致非辐射扭曲内电荷转移（TICT）态的数量减少。在没有这些空腔的DNA中不可能发生这种堆积相互作用。这一特性可用于以高选择性和灵敏度识别DNA空腔。我们期望ThT靶向这些DNA结构的能力有潜力被开发成用于DNA传感器或设备的实用且功能性生物材料。
