Transition on the entropic elasticity of DNA induced by intercalating molecules
Transition on the entropic elasticity of DNA induced by intercalating molecules
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DOI：
10.1063/1.2768945
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发表时间：
2007-09-14
影响因子：
4.4
通讯作者：
Mesquita, O. N.
中科院分区：
文献类型：
--
作者：
Rocha, M. S.;Ferreira, M. C.;Mesquita, O. N.
我们利用光镊对DNA分子与药物柔红霉素和溴化乙锭相互作用时的拉伸实验进行了研究。我们的研究结果表明，DNA-药物复合物的持续长度增加强烈的药物浓度增加到某个临界值。超过这个临界值，持续长度突然减小，并保持近似恒定的较大的药物浓度，至少在我们的实验中使用的浓度范围内。测得的嵌入剂的临界浓度的持久性长度过渡的螺旋-卷曲过渡的DNA-药物复合物从沉降实验中获得的报告值相一致。分子的轮廓长度随着药物浓度的增加而单调增加并饱和。邻居排斥模型适合我们的结果，总药物浓度作为轮廓长度的相对增加的函数。
We use optical tweezers to perform stretching experiments on DNA molecules when interacting with the drugs daunomycin and ethidium bromide, which intercalate the DNA molecule. Our results show that the persistence length of the DNA-drug complexes increases strongly as the drug concentration increases up to some critical value. Above this critical value, the persistence length decreases abruptly and remains approximately constant for larger drug concentrations, at least in the concentration range used in our experiments. Measured intercalators critical concentrations for the persistence length transition coincide with the reported values for the helix-coil transition of DNA-drug complexes obtained from sedimentation experiments. The contour length of the molecules increases monotonically and saturates as the drug concentration increases. The neighbor exclusion model fits to our results for the total drug concentration as a function of the relative increase of the contour length.