Effect of on on the overstretching transition of double-stranded DNA: Evidence of force-induced DNA melting
Effect of on on the overstretching transition of double-stranded DNA: Evidence of force-induced DNA melting
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DOI：
10.1016/s0006-3495(01)76066-3
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发表时间：
2001-02-01
影响因子：
3.4
通讯作者：
Bloomfield, VA
中科院分区：
文献类型：
--
作者：
Williams, MC;Wenner, JR;Bloomfield, VA
当双链DNA的单个分子被拉伸超过其b型轮廓长度时，测得的力显示出高度合作的过拉伸过渡。我们通过改变溶液pH来研究这种转变的来源。当溶液pH在250 mM NaCl中从pH 6.0增加到pH 10.6时，过度拉伸的转变力从67.0 +/- 0.8 pN下降到56.2 +/- 0.8 pN，而转变宽度几乎保持不变。当pH从pH 6.0降低到pH 3.1时，超拉伸力从67.0 +/- 0.8 pN降低到47.0 +/- 1.0 pN，但过渡宽度从3.0 +/- 0.6 pN增加到16.0 +/- 3 pN，这些结果在定量上与一个模型一致，即DNA链在过拉伸过渡过程中发生解离或熔化。
When a single molecule of double-stranded DNA is stretched beyond its B-form contour length, the measured force shows a highly cooperative overstretching transition. We have investigated the source of this transition by altering helix stability with solution pH. As solution pH was increased from pH 6.0 to pH 10.6 in 250 mM NaCl, the overstretching transition force decreased from 67.0 +/- 0.8 pN to 56.2 +/- 0.8 pN, whereas the transition width remained nearly constant. As the pH was lowered from pH 6.0 to pH 3.1, the overstretching force decreased from 67.0 +/- 0.8 pN to 47.0 +/- 1.0 pN, but the transition width increased from 3.0 +/- 0.6 pN to 16.0 +/- 3 pN, These results quantitatively agree with a model that asserts that DNA strand dissociation, or melting, occurs during the overstretching transition.