DNA conformational dynamics in polymer solutions above and below the entanglement limit.
DNA conformational dynamics in polymer solutions above and below the entanglement limit.
复制标题
聚合物溶液中高于和低于缠结极限的 DNA 构象动力学。
DOI：
10.1021/ac00102a018
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发表时间：
1995
影响因子：
7.4
通讯作者：
Morris,MD
中科院分区：
文献类型：
--
作者：
Shi,X;Hammond,RW;Morris,MD
在羟乙基纤维素(HEC)筛选缓冲液中进行电泳的核酸(DNA)的视频显微镜显示了DNA和HEC分子之间以前没有观察到的形状变化的相互作用。我们首次直观地展示了DNA与一个或几个离散的HEC分子之间的纠缠，这种纠缠被认为发生在超稀聚合物溶液中。通常，在稀溶液和适当缠绕的HEC溶液中，核酸似乎只在单个区域与HEC缠绕在一起。通过对图像数据的分析，揭示了DNA分子质心速度的涨落及其与构象的关系。这些观察结果解释了最近报道的在超稀羟乙基纤维素溶液和羟乙基纤维素/聚氧乙烷溶液中核酸的快速、高分辨率直流和脉冲场毛细管电泳法的成功。在含有线性聚合物溶液的缓冲液(通常称为筛分缓冲液)中的毛细管电泳对于分离用于筛分缓冲液的各种聚合物的单链和双链DNA1越来越重要，衍生化纤维素显得特别有吸引力，因为含有纤维素的缓冲液的低粘度允许高速分离。最近的研究表明，当纤维素浓度接近1/2，并且至少比纠缠极限低一个数量级时，可以实现良好的分离。3即使在这些超稀缓冲条件下，场反转也能减少带宽并提高分辨率。4‘5这些发现与传统的筛分缓冲液中凝胶电泳法的理论不同。传统的理论假设了网络的互锁结构，通过这些网络，核酸可以作为球体移动，能够穿过网络中的开口(奥格斯顿模型)6，如果球体太大，则通过旋转。7 Viovy和Duke8试图用Ogston模型的一种变体来解释DNA在超稀聚合物溶液中的电泳行为。他们的结论是，在非缠绕的聚合物溶液中，只要单个聚合物链充当DNA分子必须绕过的障碍，核酸分离就是可能的。Barron等人。%2%3已放弃
Video microscopy of nucleic acids (DNA) undergoing electrophoresis in hydroxyethyl cellulose (HEC) sieving buffers demonstrates previously unobserved shape-changing interactions between DNA and HEC molecules. We provide the first visual demonstration of entanglement between DNA and one or several discrete HEC molecules, which has been postulated to occur in ultradilute polymer solutions. Typically, nucleic acids appear to become entangled with HEC at a single region only, in both dilute and fitlly entangled HEC solutions. Fluctuations of the center of mass velocity of a DNA molecule and its correlation with conformation are revealed from analyses of the image data. These observations account for the success of recently reported rapid, high-resolution dc and pulsed-field capillary electrophoretic separations of nu-cleic acids in ultradilute hydroxyethyl cellulose solutions and hydroxyethyl cellulose/poly (ethylene oxide) solutions.Capillary electrophoresis in buffers containing solutions of linear polymers (commonly called sieving buffers) is increasingly important for separation of both single-stranded and doublestranded DNA1 Of the various polymers used in sieving buffers, derivatized cellulose appears to be especially attractive because the low viscosities of cellulose-containing buffers allow high-speed separations. Recently it has been shownthat good separations are possible at cellulose concentrations near1 2 and at least an order of magnitude below the entanglement limit. 3 Field inversion functions to decrease bandwidths and improveresolution even under these ultradilute buffer conditions. 4'5 Thesefindings are at variance with conventional theories of gel electrophoresis in sieving buffers. The conventional theories postulate networks of interlocking structures through which nucleic acids migrate either as spheres able to fit through the openings in the network (Ogston model) 6 or, if they are too large, thenby reptation. 7 Viovy andDuke8 have attempted to explainelectrophoretic behaviors of DNA in ultradilute polymer solution by a variant of the Ogston model. They concluded that nucleic acid separations are possible in nonentangled polymer solutions as long as individual polymer chains function as obstacles aroundwhich the DNA molecules musttravel. Barron et al. 2 3 abandoned the