标题： 通过金簇量尺揭示的折纸DNA拉伸分析 显示英文标题

标题： Analysis of Accordion DNA Stretching Revealed by The Gold Cluster Ruler

摘要： 一种用于测量溶液中分子内距离的有前途的新方法利用了金纳米晶体标记物之间的小角X射线散射干涉（Mathew-Fenn等，科学，322，446（2008））。当应用于双链DNA时，它揭示了DNA长度波动非常强烈，并且至少在80个碱基对步骤内具有相关性。换句话说，DNA表现得像手风琴 bellows，远距离片段协同拉伸和收缩。然而，这一假设与早期的实验和计算观察结果相矛盾。这封信表明，通过考虑团簇排除体积并假设它们之间存在适度的长程排斥力，可以合理解释这种差异。长程相互作用可能来源于靠近DNA表面的离子排除效应和团簇极化。 显示英文摘要

摘要： A promising new method for measuring intramolecular distances in solution uses small-angle X-ray scattering interference between gold nanocrystal labels (Mathew-Fenn et al, Science, 322, 446 (2008)). When applied to double stranded DNA, it revealed that the DNA length fluctuations are strikingly strong and correlated over at least 80 base pair steps. In other words, the DNA behaves as accordion bellows, with distant fragments stretching and shrinking concertedly. This hypothesis, however, disagrees with earlier experimental and computational observations. This Letter shows that the discrepancy can be rationalized by taking into account the cluster exclusion volume and assuming a moderate long-range repulsion between them. The long-range interaction can originate from an ion exclusion effect and cluster polarization in close proximity to the DNA surface.