Interguanine hydrogen-bonding patterns in adducts with water and Zn¨Cpurine complexes (purine is 9-methyladenine and 9-methylguanine). Unexpected preference of Zn(II) for adenine-N7 over guanine-N7

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• 作者：Pilar Amo-Ochoa ; Pablo J. Sanz Miguel ; Oscar Castillo ; Michal Sabat ; Bernhard Lippert and F¨¦lix Zamora
• 关键词：Hydrogen bonding ; Nucleobase pairing ; Water clusters ; Zinc complexes
• 刊名：Journal of Biological Inorganic Chemistry
• 出版年：2007
• 出版时间：May, 2007
• 年：2007
• 卷：12
• 期：4
• 页码：543-555
• 全文大小：502 KB

文摘

Guanine–guanine hydrogen bonding involving the Watson–Crick edge [N(1)H, N(2)H₂] of one base and the Hoogsteen edge (N7, O6) of the other is the dominant association pattern in the solid-state structures of two hydrates of 9-ethylguanine (9-EtGH), and in adducts of 9-methylguanine (9-MeGH) with the Zn compounds [ZnCl₂(H₂O)(9-MeGH-N7)]¡¤(9-MeGH) as well as [ZnCl₂(H₂O)(9-MeA-N7)]¡¤2(9-MeGH) (9-MeA is 9-methyladenine). The structures of 9-EtGH¡¤2H₂O and 9-EtGH¡¤3.5H₂O are dominated by polymeric tape structures of the guanine and extended water clusters. In [ZnCl₂(H₂O)(9-MeGH-N7)]¡¤(9-MeGH) the metalated guanine is involved in hydrogen bonding (GG3 motif) with a free 9-MeGH, which in turn is centrosymmetrically related to itself via hydrogen bonds involving N(2)H₂ and N3 (GG4 motif). In [ZnCl₂(H₂O)(9-MeA-N7)]¡¤2(9-MeGH) the metalated adenine base interacts via its Watson–Crick edge [N1, N(6)H₂] with the sugar edge [N(2)H₂, N3] of one of the guanine nucleobases of the GG pair. Crystallization of [ZnCl₂(H₂O)(9-MeA-N7)]¡¤2(9-MeGH) from an aqueous solution containing 9-MeGH, 9-MeA, and ZnCl₂ is fully unexpected in that the anticipated preference of Zn(II) for guanine-N7 is not realized and instead coordination to adenine-N7 is observed. The relevance of [ZnCl₂(H₂O)(9-MeGH-N7)]¡¤(9-MeGH) and [ZnCl₂(H₂O)(9-MeA-N7)]¡¤2(9-MeGH) for metal-containing nucleic acid triplex structures is discussed.