Conformational Change of Giant DNA with Added Salt As Revealed by Single Molecular Observation

详细信息    查看全文

• 作者：Naoko Makita ; Magnus Ullner ; Kenichi Yoshikawa
• 刊名：Macromolecules
• 出版年：2006
• 出版时间：September 5, 2006
• 年：2006
• 卷：39
• 期：18
• 页码：6200 - 6206
• 全文大小：136K
• 年卷期：v.39,no.18(September 5, 2006)
• ISSN：1520-5835

文摘

The structural change of individual giant double-stranded T4 DNA (165.6 kilobase pairs) moleculesas a function of salt concentration was investigated by single molecular observation with fluorescence microscopyin a wide range of concentration of NaCl, 1 × 10^-6-3 M. The measured long-axis length was transformed intoa persistence length and subjected to a power-law analysis, which showed that the electrostatic contribution tothe persistence length is inversely proportional to the square root of the salt concentration; i.e., it has a lineardependence on the screening length. This is interpreted as the behavior of a flexible chain with electrostaticexcluded-volume interactions. Although double-stranded DNA is locally stiff, it displays flexibility when thecontour length is much longer than the persistence length, as is the case for T4 DNA.