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

作者：Berdakin Matias; Steinmetz Vincent; Maitre Philippe; Pino Gustavo A^*

来源：Journal of Physical Chemistry A, 2014, 118(21): 3804-3809.

DOI：10.1021/jp5038969

The study of metal ion-DNA 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 center dot center dot center dot Ag+center dot center dot center dot cytosine (C-Ag+-C) 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-H+-C dimer responsible for the stabilization of the i-motif structure in DNA, with the replacement of the NH center dot center dot center dot N bond by a stronger N center dot center dot center dot Ag+center dot center dot center dot N bond. Moreover, since the structure of the C-Ag+-C complex is planar, it allows an optimum intercalation between pairs of the two antiparallel strand duplex in the DNA i-motif structure.

• 出版日期2014-5-29