Departamento de Química, Universidad de Burgos, 09001 Burgos, Spain.
Org Biomol Chem. 2012 Apr 7;10(13):2594-602. doi: 10.1039/c2ob06889c. Epub 2012 Feb 23.
A thermodynamic and kinetic study on the mode of binding of 9-amino-6-chloro-2-methoxi-acridine (ACMA) to poly(dA-dT)·poly(dA-dT) and poly(dG-dC)·poly(dG-dC) has been undertaken at pH = 7.0 and I = 0.1 M. The spectrophotometric, kinetic (T-jump), circular dichroism, viscometric and calorimetric information gathered point to formation of a fully intercalated ACMA complex with poly(dA-dT)·poly(dA-dT) and another one only partially intercalated (7%) with poly(dG-dC)·poly(dG-dC). The ACMA affinity with the A-T bases was higher than with the G-C bases. The two polynucleotide sequences give rise to external complexes when the ACMA concentration is raised, namely, the electrostatic complex poly(dA-dT)·poly(dA-dT)-ACMA and the major groove binding complex poly(dG-dC)·poly(dG-dC)-ACMA. A considerable quenching effect of the ACMA fluorescence is observed with poly(dA-dT)·poly(dA-dT), ascribable to face-to-face location in the intercalated A-T-ACMA base-pairs. The even stronger effect observed in the presence of poly(dG-dC)·poly(dG-dC) is related to the guanine residue from on- and off-slot ACMA positions.
在 pH = 7.0 和 I = 0.1 M 的条件下，研究了 9-氨基-6-氯-2-甲氧基吖啶（ACMA）与聚（dA-dT）·聚（dA-dT）和聚（dG-dC）·聚（dG-dC）结合模式的热力学和动力学。通过分光光度法、动力学（T-jump）、圆二色性、黏度和量热学信息收集表明，与聚（dA-dT）·聚（dA-dT）形成了完全嵌入的 ACMA 复合物，与聚（dG-dC）·聚（dG-dC）形成了仅部分嵌入（7%）的复合物。ACMA 与 A-T 碱基的亲和力高于与 G-C 碱基的亲和力。当 ACMA 浓度升高时，这两种多核苷酸序列会产生外部复合物，即静电复合物聚（dA-dT）·聚（dA-dT）-ACMA 和主沟结合复合物聚（dG-dC）·聚（dG-dC）-ACMA。聚（dA-dT）·聚（dA-dT）对 ACMA 荧光有相当大的猝灭效应，归因于嵌入的 A-T-ACMA 碱基对中的面对面位置。在存在聚（dG-dC）·聚（dG-dC）的情况下观察到更强的效应，这与来自 ON 和 OFF 插槽 ACMA 位置的鸟嘌呤残基有关。
