Figure 1.

The analyzed DNA fragment, a dinucleotide without its 5′ phosphate, is drawn in black and is referred to as a step. Its structure is represented by the nine torsion angles δ, ∊, ζ, α₁, β₁, γ₁, δ₁, χ and χ₁; the atoms defining the torsions are labelled. dTG is shown here; all 16 possible dinucleotide sequences were included in the study.