[Refinement of the A- and B-forms of DNA by the atom-atomic potential founctions method]

Structures of poly(dA). poly(dT), poly[d(A-T)].poly[d(T-A)], and poly (dG). poly (dC) were refined by an empirical method, taking into account flexible sugar moieties and simmetry conditions of DNA. The energetical optimal forms were found using Arnott's forms as starting points. These forms were shown to depend only slightly on the polynucleotide type and sequence, and characterized by C(2') endo-C(3') endo and the polynucleotide type and sequence, and characterized by C(2') endo-C(3') endo and C(3') endo and C(3') endo-C(2') endo sugar conformations. The resulting structures have the helix parameters corresponding to X-ray findings and characterized by augment resemblance between structural parameters (dichedral angles and sugar conformation) of A- and B-basic DNA forms.