作者：Shuxun Cui*, Christian Albrecht, Ferdinand Kühner, Hermann E. Gaub
关键字：DNA, single molecule
论文来源：期刊
具体来源：J. Am. Chem. Soc. 2006, 128, 6636-6639
发表时间：2006年
In this paper, we measure the single chain elasticity of an oligomer ssDNA in both aqueous and non-aqueous, apolar liquid environments by AFM-based single molecule force spectroscopy. We find a marked deviation between the force-extension relations recorded in the two ambients. This difference is attributed to the additional energy required to break the H-bond directed water bridges around ssDNA chain in aqueous solutions, which are non-existent in organic solvents. The results obtained in8Mguanidine-HCl solution provide another evidence that water bridges around ssDNA originate the observed deviation. Based on the results obtained by an ab-initio quantum mechanics calculation, a parameter-free freely-rotating-chain model is proposed. We find that this model is in a perfect agreement with the experimental force-extension curve obtained in organic solvents, which further corroborates our assumption. Based on the experimental results, it is suggested that the weak H-bonding between ssDNA and water molecules may be a precondition for a stable dsDNA to exist in water.