Thomen Philippe, Bockelmann Ulrich, Heslot François
Laboratoire de Physique de la Matière Condensée, Ecole Normale Supérieure, 24 rue Lhomond, 75005 Paris, France.
Phys Rev Lett. 2002 Jun 17;88(24):248102. doi: 10.1103/PhysRevLett.88.248102. Epub 2002 Jun 3.
Within a single-molecule configuration, we have studied rotational drag on double stranded linear DNA by measuring the force during mechanical opening and closing of the double helix at different rates. The molecule is cranked at one end by the effect of unzipping and is free to rotate at the other end. In this configuration the rotational friction torque tau on double-stranded DNA leads to an additional contribution to the opening force. It is shown that the effect of rotational drag increases with the length of the molecule, is approximately proportional to the angular velocity of cranking, and we estimate that the torque tau is of the order of 1k(B)T for 10 000 base pairs of DNA cranked at 2000 turns per second.
在单分子构型中，我们通过测量双螺旋在不同速率下机械打开和关闭过程中的力，研究了双链线性DNA上的旋转阻力。分子一端因解链作用而转动，另一端可自由旋转。在这种构型下，双链DNA上的旋转摩擦扭矩τ会对打开力产生额外贡献。结果表明，旋转阻力的影响随分子长度增加而增大，大致与转动角速度成正比，并且我们估计，对于每秒转动2000圈的10000个碱基对的DNA，扭矩τ约为1k(B)T。
