Water counting: Quantitating the hydration level of paramagnetic metal ions bound to nucleotides and nucleic acids
Water counting: Quantitating the hydration level of paramagnetic metal ions bound to nucleotides and nucleic acids
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DOI：
10.1017/s1355838202014826
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发表时间：
2002-02-01
期刊：
影响因子：
4.5
通讯作者：
Britt, RD
中科院分区：
文献类型：
--
作者：
Hoogstraten, CG;Britt, RD
二价金属离子的结合在核酶和其他RNA的结构和功能中起着关键作用。反过来，特异性结合过程的能量学和动力学由水离子脱水的成本和从与大分子的内球相互作用获得的能量之间的平衡支配。在这项工作中，我们介绍了使用H-2电子自旋回波包络调制（ESEEM）的脉冲EPR技术来确定结合到核苷酸和核酸的Mn 2+离子的水合水平。Mn 2+是Mg 2+的优异结构和功能模拟物，Mg 2+是生理学感兴趣的最常见的二价离子。比较D2 O和H2O中的数据，以Mn 2+水溶液作为参比标准，可以稳健和精确地测定结合水分子的数量，从而测定RNA衍生配体的数量。应用的monoclastide模型MnGMP和MnATP的例子，以及范式RNA系统tRNA（苯丙氨酸），显示。
Binding of divalent metal ions plays a key role in the structure and function of ribozymes and other RNAs. In turn, the energetics and kinetics of the specific binding process are dominated by the balance between the cost of dehydrating the aqueous ion and the energy gained from inner-sphere interactions with the macromolecule. In this work, we introduce the use of the pulsed EPR technique of H-2 Electron Spin-Echo Envelope Modulation (ESEEM)to determine the hydration level of Mn2+ ions bound to nucleotides and nucleic acids. Mn2+ is an excellent structural and functional mimic for Mg2+ the most common divalent ion of physiological interest. Comparison of data in D2O and H2O, with aqueous Mn2+ as a reference standard, allows a robust and precise determination of the number of bound water molecules, and therefore the number of RNA-derived ligands. Examples of applications to the mononucleotide models MnGMP and MnATP, as well as to the paradigmatic RNA system tRNA(Phe), are shown.