Nagapriya K S, Raychaudhuri A K, Chatterji Dipankar
Department of Physics, Indian Institute of Science, Bangalore 560 012, India.
Phys Rev Lett. 2006 Jan 27;96(3):038102. doi: 10.1103/PhysRevLett.96.038102. Epub 2006 Jan 25.
In this Letter, we report direct measurement of large low frequency temperature fluctuations in double stranded DNA when it undergoes a denaturation transition. The fluctuation, which occurs only in the temperature range where the denaturation occurs, is several orders more than the expected equilibrium fluctuation. It is absent in single stranded DNA of the same sequence. The fluctuation at a given temperature also depends on the wait time and vanishes in a scale of a few hours. It is suggested that the large fluctuation occurs due to coexisting denaturated and closed base pairs that are in dynamic equilibrium due to the transition through a potential barrier in the scale of 25-30kBT0 (T0=300 K).
在本信函中，我们报告了双链DNA在发生变性转变时大的低频温度波动的直接测量结果。这种波动仅发生在变性发生的温度范围内，比预期的平衡波动大几个数量级。相同序列的单链DNA中不存在这种波动。给定温度下的波动还取决于等待时间，并在几小时的时间尺度内消失。有人提出，这种大的波动是由于共存的变性碱基对和封闭碱基对通过25 - 30kBT0（T0 = 300K）尺度的势垒发生转变而处于动态平衡所致。
