DIRECT MECHANICAL MEASUREMENTS OF THE ELASTICITY OF SINGLE DNA-MOLECULES BY USING MAGNETIC BEADS
DIRECT MECHANICAL MEASUREMENTS OF THE ELASTICITY OF SINGLE DNA-MOLECULES BY USING MAGNETIC BEADS
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DOI：
10.1126/science.1439819
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发表时间：
1992-11-13
期刊：
影响因子：
56.9
通讯作者：
BUSTAMANTE, C
中科院分区：
文献类型：
--
作者：
SMITH, SB;FINZI, L;BUSTAMANTE, C
单个DNA分子的一端以化学方式连接到玻璃表面，另一端连接到磁珠上。当珠子受到已知的磁力和流体动力作用时，在光学显微镜下观察到珠子的平衡位置。在力为10(-14)到10(-11)牛顿之间的三种不同的盐浓度下，得到了单个DNA分子的拉伸-力曲线。与自由连接链模型预测的力曲线的偏差表明，DNA在溶液中具有明显的局部曲率。溴化乙锭和4‘，6-二氨基-2-苯基吲哚对分子的弹性响应影响不大，但可以直接测量它们的插层程度。相反，顺式氯铂(II)的弯曲诱导效应很大，支持DNA的自然弯曲假说。
Single DNA molecules were chemically attached by one end to a glass surface and by their other end to a magnetic bead. Equilibrium positions of the beads were observed in an optical microscope while the beads were acted on by known magnetic and hydrodynamic forces. Extension versus force curves were obtained for individual DNA molecules at three different salt concentrations with forces between 10(-14) and 10(-11) newtons. Deviations from the force curves predicted by the freely jointed chain model suggest that DNA has significant local curvature in solution. Ethidium bromide and 4',6-diamidino-2-phenylindole had little effect on the elastic response of the molecules, but their extent of intercalation was directly measured. Conversely, the effect of bend-inducing cis-diamminedichloroplatinum (II) was large and supports the hypothesis of natural curvature in DNA.