Base stacking in the penultimate base step. The stacking interactions in the 5′-GU-3′/3′-UG-5′ step have a bonus in the
thermodynamic parameters for prediction rules for consecutive terminal G·U pairs. The free energy values (ΔG37
0) are for the duplex measured in 1 M NaCl, 10 mM sodium cacodylate, and 0.1 mM
Na2EDTA, pH 7.15 Cross-strand G stacking occurs in the 5′-UG-3′/3′- GU-5′ steps, and there is a clear contrast in the sequence-dependent base-stacking. The base stacking geometries are from structures that were predicted by ROSIE41 and are consistent with all crystallography and NMR dat