Doktycz M J, Benight A S, Sheardy R D
Department of Chemistry, University of Illinois, Chicago 60680.
J Mol Biol. 1990 Mar 5;212(1):3-6. doi: 10.1016/0022-2836(90)90297-Y.
We report analysis of the NaCl-induced B-Z transition in a 16 base-pair duplex DNA with sequence designed such that when NaCl is increased the left half of the molecule undergoes the B-Z transition while the right half remains in the B-form. An equilibrium thermodynamic model based on the body of available published experimental data and the recent theoretical work of Soumpasis, which indicate, in the salt range above approximately 0.9 M-NaCl, the transition free-energy of B-Z conversion in DNA is a linear function of the NaCl concentration, is employed. Analysis of the B-Z transition of the junction-containing molecule indicates the B-Z junction formed in this 16 base-pair DNA is composed of approximately three base-pairs and has a free energy of formation of approximately 4.7 kcal/mol junction. These values for the junction are in excellent agreement with published estimates of B-Z junction size and energy derived from much longer DNA pieces.
我们报告了对一段16个碱基对的双链DNA中NaCl诱导的B-Z转变的分析，该DNA的序列设计成当NaCl浓度增加时，分子的左半部分发生B-Z转变，而右半部分保持B型。我们采用了一个基于现有已发表实验数据以及苏姆帕西斯近期理论工作的平衡热力学模型，这些数据和工作表明，在高于约0.9M-NaCl的盐浓度范围内，DNA中B-Z转变的自由能是NaCl浓度的线性函数。对含连接点分子的B-Z转变分析表明，在这段16个碱基对的DNA中形成的B-Z连接点由大约三个碱基对组成，连接点的形成自由能约为4.7千卡/摩尔连接点。这些连接点的值与从长得多的DNA片段得出的已发表的B-Z连接点大小和能量估计值非常吻合。
