Departamento de Física, Universidade Federal de Viçosa, Viçosa, Minas Gerais, 36570-900, Brazil and Departamento de Física, Universidade Federal de Juiz de Fora, Juiz de Fora, Minas Gerais, 36036-900, Brazil.
Departamento de Física, Universidade Federal de Viçosa, Viçosa, Minas Gerais, 36570-900, Brazil and Departamento de Formação Geral, Centro Federal de Educação Tecnológica de Minas Gerais, Curvelo, Minas Gerais, 35790-000, Brasil.
Phys Rev E. 2020 Sep;102(3-1):032401. doi: 10.1103/PhysRevE.102.032401.
We present a new study on the interaction of the DNA molecule with the surfactant dodecyltrimethylammonium bromide (DTAB), performed mainly with optical tweezers. Single-molecule force spectroscopy experiments performed in the low-force entropic regime allowed a robust characterization of the DNA-DTAB interaction, unveiling how the surfactant changes the mechanical properties of the biopolymer, the binding parameters, and the competition of the two mechanisms involved in the interaction: electrostatic attraction between the cationic surfactant heads and the negative phosphate backbone of the DNA and hydrophobic interactions between the tails of the bound DTAB molecules, which can result in DNA compaction in solution depending on the quantity of bound surfactant. Finally, force clamp experiments with magnetic tweezers and gel electrophoresis assays confirm that DTAB compacts DNA depending not only on the surfactant concentration but also on the conformation of the biopolymer in solution. The present study provides new insights on general aspects of the DNA-surfactant complexes formation, contributing to the fundamental knowledge of the physics of such interactions.
我们提出了一项关于 DNA 分子与表面活性剂十二烷基三甲基溴化铵（DTAB）相互作用的新研究，主要使用光学镊子进行。在低力熵状态下进行的单分子力谱实验能够对 DNA-DTAB 相互作用进行稳健的表征，揭示了表面活性剂如何改变生物聚合物的机械性能、结合参数以及相互作用中涉及的两种机制的竞争：阳离子表面活性剂头与 DNA 的负磷酸盐骨架之间的静电吸引力和结合的 DTAB 分子尾部之间的疏水力，这可能导致 DNA 在溶液中发生压缩，具体取决于结合的表面活性剂的量。最后，使用磁镊的力钳实验和凝胶电泳分析证实，DTAB 不仅可以根据表面活性剂浓度，还可以根据溶液中生物聚合物的构象来压缩 DNA。本研究为 DNA-表面活性剂复合物形成的一般方面提供了新的见解，有助于此类相互作用的物理基础的基本知识。
