PROBABILITY OF DNA KNOTTING AND THE EFFECTIVE DIAMETER OF THE DNA DOUBLE HELIX
PROBABILITY OF DNA KNOTTING AND THE EFFECTIVE DIAMETER OF THE DNA DOUBLE HELIX
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DOI：
10.1073/pnas.90.11.5307
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发表时间：
1993-06-01
影响因子：
11.1
通讯作者：
VOLOGODSKII, AV
中科院分区：
文献类型：
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作者：
RYBENKOV, VV;COZZARELLI, NR;VOLOGODSKII, AV
在长链聚合物的无规环化过程中，会形成不同类型的结。我们通过实验研究了噬菌体P4 DNA通过其长的粘性末端随机环化产生的结型的分布。最简单的结(三叶结)占优势，但也检测到更复杂的结。随着溶液中Na+浓度的降低，结节的比例大大降低。通过将这些实验结果与计算机模拟的打结概率进行比较，我们计算了DNA双螺旋的有效直径。这个重要的排除体积参数是DNA分子片段之间静电斥力的量度。计算的有效DNA直径是电解质浓度的敏感函数，比低一价阳离子浓度溶液中的几何直径大几倍。
During the random cyclization of long polymer chains, knots of different types are formed. We investigated experimentally the distribution of knot types produced by random cyclization of phage P4 DNA via its long cohesive ends. The simplest knots (trefoils) predominated, but more complex knots were also detected. The fraction of knots greatly diminished with decreasing solution Na+ concentration. By comparing these experimental results with computer simulations of knotting probability, we calculated the effective diameter of the DNA double helix. This important excluded-volume parameter is a measure of the electrostatic repulsion between segments of DNA molecules. The calculated effective DNA diameter is a sensitive function of electrolyte concentration and is several times larger than the geometric diameter in solutions of low monovalent cation concentration.