Knobloch Bernd, Sigel Helmut, Okruszek Andrzej, Sigel Roland K O
Institute of Inorganic Chemistry, University of Zürich, Winterthurerstrasse 190, CH-8057, Zürich, Switzerland.
Org Biomol Chem. 2006 Mar 21;4(6):1085-90. doi: 10.1039/b517904a. Epub 2006 Jan 26.
The dinucleotide d(pGpG) is an often employed DNA model to study various kinds of interactions between DNA and metal ions, but its acid-base properties were not yet described in detail. In this study the six deprotonation reactions of H4[d(pGpG)]+ are quantified. The acidity constants for the release of the first proton from the terminal P(O)(OH)2 group (pKa = 0.65) and for one of the (N7)H+ sites (pKa = 2.4) are estimated. The acidity constants of the remaining four deprotonation reactions were measured by potentiometric pH titrations in aqueous solution (25 degrees C; I = 0.1 M, NaNO3): The pKa values for the deprotonations of the second (N7)H+, the P(O)2(OH)-, and the two (N1)H sites are 2.98, 6.56, 9.54 and 10.11, respectively. Based on these results we show how to estimate acidity constants for related systems that have not been studied, e.g. pGpG, which is involved in the initiation step of a rotavirus RNA polymerase. The relevance of our results for nucleic acids in general is briefly indicated.
二核苷酸d(pGpG)是一种常用于研究DNA与金属离子之间各种相互作用的DNA模型，但其酸碱性质尚未得到详细描述。在本研究中，对H4[d(pGpG)]+的六个去质子化反应进行了定量。估计了从末端P(O)(OH)2基团释放第一个质子的酸度常数(pKa = 0.65)以及其中一个(N7)H+位点的酸度常数(pKa = 2.4)。其余四个去质子化反应的酸度常数通过在水溶液(25℃；I = 0.1 M，NaNO3)中的电位pH滴定法测定：第二个(N7)H+、P(O)2(OH)-和两个(N1)H位点去质子化的pKa值分别为2.98、6.56、9.54和10.11。基于这些结果，我们展示了如何估计尚未研究的相关系统的酸度常数，例如参与轮状病毒RNA聚合酶起始步骤的pGpG。简要指出了我们的结果对一般核酸的相关性。
