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首页> 外文期刊>The journal of physical chemistry, B. Condensed matter, materials, surfaces, interfaces & biophysical >Role of monovalent counterions in the ultrafast dynamics of DNA
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Role of monovalent counterions in the ultrafast dynamics of DNA

机译：单价抗衡离子在DNA超快动力学中的作用

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This paper examines the contribution of counterion motion to the electric-field dynamics in the interior of DNA. The electric field is measured by a coumarin fluorophore that is synthetically incorporated into an oligonucleotide, where it replaces a native base pair. The DNA is a 17-base-pair oligomer with no A- or G-tracts. Time-resolved Stokes-shift measurements on the coumarin are made from 40 ps to 40 ns with each of the alkali ions and or one of several tetraalkylammonium ions as the DNA counterion. With the possible exception of rubidium, there are no indications of site-specific binding of the counterions. For sodium and other ions with a smaller hydrodynamic radius, the dynamics are identical and are fit to a power law. For larger ions, there is a progressive increase in the rate of shifting after 1 ns. This effect correlates with the hydrodynamic radius of the counterion. The lack of change in the spectral shape of the emission shows that neither the broadly distributed power-law relaxation nor the extra nanosecond dynamics are due to heterogeneity in the relaxation rates of different helices.
机译：本文研究了抗衡离子运动对DNA内部电场动力学的贡献。通过香豆素荧光团测量电场，该香豆素荧光团被合成地掺入寡核苷酸中，在那里它取代了天然碱基对。 DNA是没有A或G链的17个碱基对的寡聚体。在香豆素上的时间分辨斯托克斯位移测量是在40 ps至40 ns的条件下进行的，其中每个碱金属离子和或几个四烷基铵离子之一作为DNA抗衡离子。除the外，没有迹象表明抗衡离子的位点特异性结合。对于具有较小流体动力学半径的钠离子和其他离子，动力学是相同的，并且符合幂律。对于较大的离子，在1 ns后移动速度会逐渐增加。该作用与抗衡离子的流体动力学半径有关。发射光谱形状没有变化，这表明宽分布的幂律弛豫和额外的纳秒动力学都不是由于不同螺旋的弛豫率的异质性引起的。

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