研究力诱导双链 DNA 融解与长度和构象的关系。
Study of force induced melting of dsDNA as a function of length and conformation.
机构信息
Department of Physics, Harvard University, Cambridge, MA 02138, USA.
出版信息
J Phys Condens Matter. 2010 Oct 20;22(41):414106. doi: 10.1088/0953-8984/22/41/414106. Epub 2010 Sep 30.
We measure the constant force required to melt double-stranded (ds) DNA as a function of length for lengths from 12 to 100,000 base pairs, where the force is applied to the 3'3' or 5'5' ends of the dsDNA. Molecules with 32 base pairs or fewer melt before overstretching. For these short molecules, the melting force is independent of the ends to which the force is applied and the shear force as a function of length is well described by de Gennes theory with a de Gennes length of less than 10 bp. Molecules with lengths of 500 base pairs or more overstretch before melting. For these long molecules, the melting force depends on the ends to which the force is applied. The melting force as a function of length increases even when the length exceeds 1000 bp, where the length dependence is inconsistent with de Gennes theory. Finally, we expand de Gennes melting theory to 3'5' pulling and compare the predictions with experimental results.
我们测量了双链 (ds) DNA 熔化所需的恒定力，其长度范围从 12 到 100,000 个碱基对，力施加在 dsDNA 的 3'3' 或 5'5' 末端。长度为 32 个碱基对或更短的分子在过度拉伸之前就会熔化。对于这些短分子，熔化力与施加力的末端无关，剪切力与长度的关系很好地符合德热纳理论，德热纳长度小于 10 bp。长度为 500 个碱基对或更长的分子在熔化之前会过度拉伸。对于这些长分子，熔化力取决于施加力的末端。即使长度超过 1000 bp，熔化力随长度的变化仍在增加，这与德热纳理论不一致。最后，我们将德热纳熔化理论扩展到 3'5' 拉伸，并将预测结果与实验结果进行比较。
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