Exploring a DNA Sequence for the Three-Dimensional Structure Determination of a Silver(I)-Mediated C-C Base Pair in a DNA Duplex By (1)H NMR Spectroscopy.

Recently, we discovered novel silver(I)-mediated cytosine–cytosine base pair (C–AgI–C) in DNA duplexes. To understand the properties of these base pairs, we searched for a DNA sequence that can be used in NMR structure determination. After extensive sequence optimizations, a non-symmetric 15-base-paired DNA duplex with a single C–AgI–C base pair flanked by 14 A–T base pairs was selected. In spite of its challenging length for NMR measurements (30 independent residues) with small sequence variation, we could assign most non-exchangeable protons (254 out of 270) and imino protons for structure determination.