Electronic Bio Sciences, 5754 Pacific Center Boulevard, Suite 204, San Diego, California 92121, USA.
J Am Chem Soc. 2010 Feb 17;132(6):1878-85. doi: 10.1021/ja906951g.
We present the use of an alternating current (AC) signal as a means to monitor the conductance of an alpha-hemolysin (alphaHL) pore as a DNA hairpin with a polydeoxyadenosine tail is driven into and released from the pore. Specifically, a 12 base pair DNA hairpin attached to a 50-nucleotide poly-A tail (HP-A(50)) is threaded into an alphaHL channel using a DC driving voltage. Once the HP-A(50) molecule is trapped within the alphaHL channel, the DC driving voltage is turned off and the conductance of the channel is monitored using an AC voltage. The escape time, defined as the time it takes the HP-A(50) molecule to transport out of the alphaHL channel, is then measured. This escape time has been monitored as a function of AC amplitude (20 to 250 mV(ac)), AC frequency (60-200 kHz), DC drive voltage (0 to 100 mV(dc)), and temperature (-10 to 20 degrees C), in order to determine their effect on the predominantly diffusive motion of the DNA through the nanopore. The applied AC voltage used to monitor the conductance of the nanopore has been found to play a significant role in the DNA/nanopore interaction. The experimental results are described by a one-dimensional asymmetric periodic potential model that includes the influence of the AC voltage. An activation enthalpy barrier of 1.74 x 10(-19) J and a periodic potential asymmetry parameter of 0.575 are obtained for the diffusion at zero electrical bias of a single nucleotide through alphaHL.
我们提出了使用交流（AC）信号作为一种手段来监测α-溶血素（alphaHL）孔的电导，因为带有聚脱氧腺苷尾的 DNA 发夹被驱动进入和离开孔。具体来说，使用直流驱动电压将附着在 50 个核苷酸聚 A 尾巴（HP-A(50)）上的 12 个碱基对 DNA 发夹插入 alphaHL 通道。一旦 HP-A(50)分子被困在 alphaHL 通道内，就关闭直流驱动电压，并使用交流电压监测通道的电导。然后测量 HP-A(50)分子从 alphaHL 通道中逃逸的逃逸时间。已经监测了逃逸时间作为 AC 幅度（20 至 250 mV(ac)）、AC 频率（60-200 kHz）、直流驱动电压（0 至 100 mV(dc)）和温度（-10 至 20 摄氏度）的函数，以确定它们对 DNA 通过纳米孔主要扩散运动的影响。用于监测纳米孔电导的施加交流电压已被发现对 DNA/纳米孔相互作用起着重要作用。实验结果由包括交流电压影响的一维不对称周期势模型来描述。在零电偏压下，单个核苷酸通过 alphaHL 的扩散得到了 1.74 x 10(-19) J 的激活焓势垒和 0.575 的周期势不对称参数。
