作者：Shuxun Cui,* Jin Yu, Ferdinand Kuhner, Klaus Schulten, Hermann E. Gaub*
关键字：DNA, single molecule
论文来源：期刊
具体来源：J. Am. Chem. Soc. 2007, 129, 14710-14716
发表时间：2007年

DNA displays a richness of biologically relevant supramolecular structures, which depend on both sequence and ambient. The effect of dragging dsDNA from water into poor solvent on the double-stranded structure is still unclear because of condensation. Here we employ single molecule techniques based on atomic force microscopy and molecular dynamics (MD) simulations to investigate the change in structure and mechanics of DNA during the ambient change. We found that the two strands are split apart when the dsDNA is pulled at one strand from water into a poor solvent. The findings were corroborated by MD simulations where dsDNA is dragged from water into poor solvent, revealing details of the strand separation at the water/poor solvent interface. Because the structure of DNA is of high polarity, all poor solvents show relatively low polarity. We speculate that the principle of spontaneous unwinding/splitting of dsDNA by providing a low-polar (in other word, hydrophobic) micro-environment is exploited as one of the catalysis mechanisms of helicase.