This work concerns an analysis of the binding mechanism of a copper phthalocyanine (Alcian Blue-tetrakis(methylpyridinium) chloride, ABTP) to natural calf thymus DNA, G-quadruplexes (G4) and synthetic RNA polynucleotides in the form of double polyriboadenylic·polyribouridylic acid (poly(A)·poly(U)) or triple strands polyriboadenylic·2polyribouridylic acid (poly(A)·2poly(U)). ABTP is a well know dye that might undergo novel applications, but its interaction with DNA is scarcely studied and we lack information on possible RNA or G4 binding. This might be related to system complexity due to the presence of supramolecular dye-dye aggregates. Despite this, we show here that apparent parameters can be calculated, which provide information on the binding mechanism. Absorbance titrations in the presence of biosubstrate excess, melting and circular dichroism experiments show that ABTP binds to both RNAs and DNA. External/groove binding is the main feature for RNAs, whereas partial intercalation is the major binging mode for DNA. ABTP externally binds to both hybrid, parallel and anti-parallel G4s but seem to show a slightly different binding mode and a preference for anti-parallel structures. The thermodynamic features of the different systems are also discussed in the frame of the enthalpy-entropy compensation phenomenon.

这项工作涉及分析铜酞菁（阿尔新蓝-四（甲基吡啶）氯化物，ABTP）与天然小牛胸腺 DNA、G-四链体 (G4) 和双聚核糖腺苷·聚核糖苷酸形式的合成 RNA 多核苷酸的结合机制（聚（A）·聚（U））或三链聚核糖腺苷酸·2聚核糖苷酸（聚（A）·2聚（U））。ABTP 是一种众所周知的染料，可能会有新的应用，但很少研究它与 DNA 的相互作用，而且我们缺乏关于可能的 RNA 或 G4 结合的信息。由于超分子染料-染料聚集体的存在，这可能与系统复杂性有关。尽管如此，我们在这里展示了可以计算表观参数，这些参数提供了有关绑定机制的信息。在生物底物过量的情况下进行吸光度滴定，熔解和圆二色性实验表明 ABTP 与 RNA 和 DNA 结合。外部/凹槽结合是 RNA 的主要特征，而部分嵌入是 DNA 的主要结合模式。ABTP 外部结合混合、平行和反平行 G4，但似乎显示出略有不同的结合模式和对反平行结构的偏好。不同系统的热力学特征也在焓-熵补偿现象的框架内进行了讨论。