Technical and Macromolecular Chemistry, Paderborn University, Warburger Str. 100, 33098 Paderborn, Germany.
Int J Mol Sci. 2022 Aug 1;23(15):8547. doi: 10.3390/ijms23158547.
Guanidinium (Gdm) undergoes interactions with both hydrophilic and hydrophobic groups and, thus, is a highly potent denaturant of biomolecular structure. However, our molecular understanding of the interaction of Gdm with proteins and DNA is still rather limited. Here, we investigated the denaturation of DNA origami nanostructures by three Gdm salts, i.e., guanidinium chloride (GdmCl), guanidinium sulfate (GdmSO), and guanidinium thiocyanate (GdmSCN), at different temperatures and in dependence of incubation time. Using DNA origami nanostructures as sensors that translate small molecular transitions into nanostructural changes, the denaturing effects of the Gdm salts were directly visualized by atomic force microscopy. GdmSCN was the most potent DNA denaturant, which caused complete DNA origami denaturation at 50 °C already at a concentration of 2 M. Under such harsh conditions, denaturation occurred within the first 15 min of Gdm exposure, whereas much slower kinetics were observed for the more weakly denaturing salt GdmSO at 25 °C. Lastly, we observed a novel non-monotonous temperature dependence of DNA origami denaturation in GdmSO with the fraction of intact nanostructures having an intermediate minimum at about 40 °C. Our results, thus, provide further insights into the highly complex Gdm-DNA interaction and underscore the importance of the counteranion species.
胍（Gdm）与亲水性和疏水性基团都相互作用，因此是生物分子结构的高度有效变性剂。然而，我们对 Gdm 与蛋白质和 DNA 的相互作用的分子理解仍然相当有限。在这里，我们研究了三种 Gdm 盐，即氯化胍（GdmCl）、硫酸胍（GdmSO）和硫氰酸胍（GdmSCN）在不同温度下和孵育时间依赖性下对 DNA 折纸纳米结构的变性作用。使用 DNA 折纸纳米结构作为将小分子转变为纳米结构变化的传感器，通过原子力显微镜直接观察 Gdm 盐的变性作用。GdmSCN 是最有效的 DNA 变性剂，在 50°C 时浓度为 2 M 即可导致完全的 DNA 折纸纳米结构变性。在如此苛刻的条件下，变性在 Gdm 暴露的最初 15 分钟内发生，而在 25°C 时较弱的变性盐 GdmSO 则观察到较慢的动力学。最后，我们观察到在 GdmSO 中 DNA 折纸纳米结构变性具有新颖的非单调温度依赖性，完整纳米结构的分数在约 40°C 时具有中间最小值。因此，我们的结果进一步深入了解了高度复杂的 Gdm-DNA 相互作用，并强调了抗衡离子种类的重要性。
