Table 2. Electrostatic potential values at cation locations in the DNA major groove.

pi–1Ni–1piNi	Ep (kT/e) for pi–1 in BI	Ep (kT/e) for pi–1 in BII
p20T20p21C21	−2.4 (0.6)	−2.2 (0.2)
p21C21p22A22	−2.7 (0.5)	−3.2 (0.6)
p22A22p23G23	−3.8 (0.7)	−4.3 (0.6)
p23G23p24A24	−3.3 (0.7)	−3.5 (0.5)
p24A24p25A25	−2.9 (0.4)	−3.2 (0.5)

Poisson-Boltzmann electrostatic potentials (Ep) were calculated for 0.5 Å sided cubes centered on the average position of Mg²⁺ observed in MD structures (Figure 1). These squares were shifted along the five N_i–1p_iN_i dinucleotide steps composing the T₂₀p₂₁C₂₁p₂₂A₂₂p₂₃G₂₃p₂₄A₂₄p₂₅A₂₅ fragment. The potentials are sorted according to the conformational state of p_i–1. A total of 100 snapshots extracted from S1 were examined. Standard deviations are given in parentheses.