Bernués J, Beltrán R, Casasnovas J M, Azorín F
Grupo de Química Macromolecular, Centro de Investigación y Desarrollo CSIC, ETSEIB, Barcelona, Spain.
Nucleic Acids Res. 1990 Jul 25;18(14):4067-73. doi: 10.1093/nar/18.14.4067.
The homopyrimidine-homopurine sequence d(CT/GA)22 undergoes, in the presence of zinc ions, transition to an altered DNA conformation (*H-DNA) which is neither H-DNA nor B-DNA. *H-DNA is characterized by a peculiar chemical reactivity pattern in which most of the polypyrimidine strand is hyperreactive to osmium tetroxide and the central part of the polypurine strand is sensitive to diethylpyrocarbonate. Formation of *H-DNA is specific of metal-ion. *H-DNA is detected in the presence of Zn++, Cd++ and Mn++. The efficiency on promoting the transition is in the order of Zn++ greater than Cd++ much greater than Mn++. Formation of *H-DNA is also specific of nucleotide sequence. From all the different homopolymeric sequences tested only the d(CT/GA)22 sequence showed the zinc-induced transition to *H-DNA. These results suggest that stabilization of *H-DNA involves the formation of a specific complex between the metal-ion and the nucleotide sequence. The biological relevance of these results is discussed in view of the important role that zinc ions play on many nucleic acids processes.
同嘧啶-同嘌呤序列d(CT/GA)22在锌离子存在下会转变为一种既非H-DNA也非B-DNA的改变的DNA构象（*H-DNA）。*H-DNA的特征在于一种特殊的化学反应模式，其中大部分多嘧啶链对四氧化锇高度反应，而多嘌呤链的中心部分对焦碳酸二乙酯敏感。H-DNA的形成具有金属离子特异性。在Zn++、Cd++和Mn++存在下可检测到H-DNA。促进转变的效率顺序为Zn++大于Cd++远大于Mn++。H-DNA的形成也具有核苷酸序列特异性。在所有测试的不同同聚序列中，只有d(CT/GA)22序列显示出锌诱导的向H-DNA的转变。这些结果表明，*H-DNA的稳定涉及金属离子与核苷酸序列之间形成特定复合物。鉴于锌离子在许多核酸过程中发挥的重要作用，讨论了这些结果的生物学相关性。
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