Electron density maps of d(ATTAAT)2.
2Fo-Fc electron density maps at 1σ level, with Refmac5 map sharpening : (a) stereo view of two duplexes. All base pairs are in the Hoogsteen conformation. The shift between the two duplexes is very clear at the center of the column. It is shown in detail in Fig. 4; (b) one of the central base pairs. Other base pairs have a similar map.