Figure 6.

Comparison of experimental and computed NMR chemical-shift changes. Experimental data are observed chemical-shift changes of the G_δ imino protons upon substitutions to syn residues 3, 9, 15, 16, and 21 by guanine derivatives ^BrG (circles), ^OmetG (squares), and ^AmG (diamonds). Computational data are the results of different NMR chemical-shift calculations, as shown in Table 4. The solid black line represents exact agreement between computational and experimental results. Data points are shown for every combination of experimentally observed and computed changes in chemical shift for each type of guanine derivative.