(A) Sequential NOE connectivity for the imino protons of base pairs T2·A23 → T11·A14 for the Nar1IQ3 duplex at 5 °C. The labels represent the imino proton of the designated base. (B) NOE connectivity between the imino protons and the base and amino protons. The cross-peaks involving the imino protons are labeled as: a′, a, X7 N1H → X7 NH2-2b, e; b′, b, G17 N1H → C8 NH2-4b, e; c′ and c, G19 N1H → C6 NH2-4b, e; 1, G17 N1H → X7 H4A; 2, G17 N1H → X7 H5A. (C) NOE connectivity between the imino and the IQ methyl protons. The IQ-DNA cross-peaks labeled are as: 3, G17 N1H → X7 CH3; and 4, G19 N1H → X7 CH3.