Figure 2.

(A) The A₃T₂ DNA sequence used in this study. ^2′FU indicates 2′-fluoro-2′-deoxyuridine and the dot between T18 and T19 denotes a phosphorothioate. (B) Expanded view of A₃T₂ DNA showing label positions corresponding to standard and P-F REDOR measures of minor groove width across the central A₃T₂ tract. The dark sphere at upper right marks the i phosphate (T19); on the lower left, the dark sphere indicates the i + 3 phosphate (T8), while the light sphere indicates the 2′F label used in the present experiments. The standard B-form DNA model for the A₃T₂ oligomer was generated using the biopolymer module of Insight II (Biosym). (C) Stereoview of the free A₃T₂ DNA generated using Insight II. Dark spheres show location of phosphorothioate and ^2′FU.