Fernández-Sierra Mónica, Delgado-Martí Violeta, Colón-García Jorge E, Quiñones Edwin
Department of Chemistry, University of Puerto Rico, Río Piedras Campus, San Juan, Puerto Rico 00936-8377.
Chem Phys. 2011 May 26;383(1-3):50-55. doi: 10.1016/j.chemphys.2011.04.007.
We present a single-molecule method for measuring the torque exerted by braided DNA molecules undergoing spontaneous unbraiding while attached to a paramagnetic dumbbell in the absence of external manipulation. A magnetic tweezers setup is employed to braid pairs of lambda DNA molecules covalently bound to a surface. Upon removing the magnetic field, the braided DNA molecules undergo spontaneous unbraiding, efficiently transforming the stored elastic energy into enough mechanical energy to rotate the tethered dumbbells for periods as long as 30 minutes. Using hydrodynamic equations we estimate the torque exerted on the dumbbells by the DNA braids, yielding values ranging from 47 to 166 pN nm.
我们提出了一种单分子方法，用于测量在没有外部操控的情况下，附着于顺磁哑铃的编织DNA分子在自发解编过程中所施加的扭矩。采用磁镊装置对共价结合到表面的λDNA分子对进行编织。去除磁场后，编织的DNA分子会自发解编，有效地将储存的弹性能转化为足够的机械能，使系留的哑铃旋转长达30分钟。利用流体动力学方程，我们估算了DNA编织物对哑铃施加的扭矩，得出的值在47至166皮牛纳米之间。
