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Fig. 1. NS3 unwinds DNA in 3-bp steps. (A) PD1, a DNA with 18 double strands (ds)
and 20 single strands (ss), was labeled with donor (Cy3) and acceptor (Cy5)
at the ds-ss junction and was tethered to a polyethylene glycol surface by
3'''''''' biotin. (B) Cy3 (green) and Cy5 (red) intensities monitored during unwinding
of a single PD1 molecule (raw time traces in light color, three-point averaged
traces in dark color). (C) Calculated FRET efficiency versus time for
the molecule shown in (B). (D and E) Two more examples of FRET traces of
PD1. (F) PD2 is thesameconstruct as in (A) but prepared with dyes in the middle of
duplex. (G to J) Plots analogous to those in (B) to (E) for PD2.
科学网2007年8月2日消息 据生物谷报道,最近，研究人员确定了一个对丙肝病毒 DNA复制至关重要的酶的机制。这个名为NS3的酶是新的丙肝治疗法的靶标，它的作用是打开 DNA和RNA使其得以复制。该研究结果发表在最新一期的《科学》杂志上。
Sua Myong和同事用单分子光谱学方法观察了NS3沿丙肝病毒 DNA双螺旋的“蠕动”。这个酶每步打开三个 DNA碱基对。(碱基对是 DNA双股上对应的由氢键连接的核苷酸。)但是，在碱基对打开之前，还有隐藏的步骤。这个酶先是一、二大步、然后一个小步爬上碱基对，直到张力足够大从而导致解卷和三个碱基对看起来是同时的开链。
NS3酶的作用机制的揭示，对于研究丙肝病毒 DNA的复制过程具有重要的指导作用。
原文出处： Science 27 July 2007 Vol 317, Issue 5837
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特定基因拷贝数不同造就人