Gas Phase Structure of Metal Mediated (Cytosine)2Ag+ Mimics the Hemiprotonated (Cytosine)2H+ Dimer in i-Motif Folding

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• 作者：Matias Berdakin ; Vincent Steinmetz ; Philippe Maitre ; Gustavo A. Pino
• 刊名：Journal of Physical Chemistry A
• 出版年：2014
• 出版时间：May 29, 2014
• 年：2014
• 卷：118
• 期：21
• 页码：3804-3809
• 全文大小：287K
• 年卷期：v.118,no.21(May 29, 2014)
• ISSN：1520-5215

文摘

The study of metal ion鈥揇NA interaction aiming to understand the stabilization of artificial base pairing and a number of noncanonical motifs is of current interest, due to their potential exploitation in developing new technological devices and expanding the genetic code. A successful strategy has been the synthesis of metal-mediated base pairs, in which a coordinative bond to a central metal cation replaces a H-bond in a natural pair. In this work, we characterized, for the first time, the gas phase structure of the cytosine路路路Ag⁺路路路cytosine (C鈥揂g⁺鈥揅) complex by means of InfraRed-MultiPhoton-Dissociation (IR-MPD) spectroscopy and theoretical calculation. The IR-spectrum was confidently assigned to one structure with the Ag⁺ acting as a bridge between the heteronitrogen atoms in each cytosine (both in the keto-amino form). This structure is biologically relevant since it mimics the structure of the hemiprotonated C鈥揌⁺鈥揅 dimer responsible for the stabilization of the i-motif structure in DNA, with the replacement of the NH路路路N bond by a stronger N路路路Ag⁺路路路N bond. Moreover, since the structure of the C鈥揂g⁺鈥揅 complex is planar, it allows an optimum intercalation between pairs of the two antiparallel strand duplex in the DNA i-motif structure.