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首页> 外文期刊>Chemistry: A European journal >Metal-ion-coordinating properties of the dinucleotide 2 '-deoxyguanylyl(5 '-> 3 ')-2 '-deoxy-5 '-guanylate (d(pGpG)(3-)): Isomeric equilibria including macrochelated complexes relevant for nucleic acids
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Metal-ion-coordinating properties of the dinucleotide 2 '-deoxyguanylyl(5 '-> 3 ')-2 '-deoxy-5 '-guanylate (d(pGpG)(3-)): Isomeric equilibria including macrochelated complexes relevant for nucleic acids

机译：二核苷酸2'-脱氧胍基（5'-> 3'）-2'-脱氧-5'-鸟苷酸（d（pGpG）（3-））的金属离子配位特性：异构平衡，包括与核酸相关的大螯合物酸

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摘要

The interaction between divalent metal ions and nucleic acids is well known, yet knowledge about the strength of binding of labile metal ions at the various sites is very scarce. We have therefore studied the stabilities of complexes formed between the nucleic acid model d(pGpG) and the essential metal ions Mg2+ and Zn2+ as well as with the generally toxic ions Cd2+ and Pb2+ by potentiometric pH titrations; all four ions are of relevance in ribozyme chemistry. A comparison of the present results with earlier data obtained for M(pUpU)(-) complexes allows the conclusion that phosphate-bound Mg2+ and Cd2+ form macrochelates by interaction with N7, whereas the also phosphate-coordinated Pb2+ forms a 10-membered chelate with the neighboring phosphate diester bridge. Zn2+ forms both types of chelates with formation degrees of about 91% and 2.4% for Zn[d(pGpG)](cl/N7)(-) and Zn[d(pGpG)](cl/PO)(-), respectively; the open form with Zn2+ bound only to the terminal phosphate group, Zn[d(pGpG)](op)(-), amounts to about 6.8%. The various intramolecular equilibria have also been quantified for the other metal ions. Zn2+, Cu2+, and Cd2+ also form macrochelates in the monoprotonated M[H;d(pGpG)] species (the proton being at the terminal phosphate group), that is, the metal ion at N7 interacts to some extent with the P(O)(2)(OH)(-) group. Thus, this study demonstrates that the coordinating properties of the various metal ions toward a pGpG unit in a nucleic acid differ: Mg2+, Zn2+, and Cd2+ have a significant tendency to bridge the distance between N7 and the phosphate group of a (d)GMP unit, although to various extents, whereas Pb2+ (and possibly Ca2+) prefer a pure phosphate coordination.
机译：二价金属离子与核酸之间的相互作用是众所周知的，但是关于不稳定金属离子在各个位点的结合强度的知识非常匮乏。因此，我们通过电位滴定法滴定法研究了核酸模型d（pGpG）与必需金属离子Mg2 +和Zn2 +以及与一般有毒离子Cd2 +和Pb2 +之间形成的配合物的稳定性;所有四个离子都与核酶化学有关。本结果与较早的M（pUpU）（-）配合物数据进行比较，得出结论，磷酸盐结合的Mg2 +和Cd2 +通过与N7的相互作用形成大螯合物，而磷酸盐配位的Pb2 +则与N7形成10元螯合物。邻近的磷酸二酯桥。 Zn2 +形成两种类型的螯合物，Zn [d（pGpG）]（cl / N7）（-）和Zn [d（pGpG）]（cl / PO）（-）的形成度分别为91％和2.4％ ;仅具有末端磷酸根基团Zn [d（pGpG）]（op）（-）的Zn2 +的开放形式约为6.8％。还已经对其他金属离子定量了各种分子内平衡。 Zn2 +，Cu2 +和Cd2 +在单质子化的M [H; d（pGpG）]物种（质子位于磷酸根末端）中也形成大螯合物，即N7处的金属离子与P（O ）（2）（OH）（-）基团。因此，这项研究表明核酸中各种金属离子对pGpG单元的配位特性不同：Mg2 +，Zn2 +和Cd2 +具有明显的趋势，可以桥接N7和（d）GMP磷酸基团之间的距离。单位，尽管程度不同，而Pb2 +（可能还有Ca2 +）更喜欢纯磷酸盐配位。

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