环状闭合过程中DNA链的打结

Knotting of a DNA chain during ring closure.

作者信息

Shaw S Y, Wang J C

机构信息

Harvard University, Department of Biochemistry and Molecular Biology, Cambridge, MA 02138.

出版信息

Science. 1993 Apr 23;260(5107):533-6. doi: 10.1126/science.8475384.

DOI:10.1126/science.8475384

PMID:8475384

Abstract

The formation of knotted species on random ring closure of two DNAs that are 5.6 kilobase pairs (kbp) and 8.6 kbp in length was measured, and these data were used to calculate the effective DNA helix diameter as a function of sodium ion and magnesium ion concentration. In the presence of more than 50 mM magnesium ion, interactions between DNA segments appear to be attractive rather than repulsive. The free energy of formation of relaxed trefoil and figure-eight DNA knots and of supercoiled trefoil DNA knots was also evaluated.

摘要

测量了长度分别为5.6千碱基对（kbp）和8.6 kbp的两条DNA随机环化时形成纽结物种的情况，并利用这些数据计算了作为钠离子和镁离子浓度函数的有效DNA螺旋直径。在存在超过50 mM镁离子的情况下，DNA片段之间的相互作用似乎是吸引性的而非排斥性的。还评估了松弛三叶结和8字结DNA纽结以及超螺旋三叶结DNA纽结形成的自由能。