Accessibility for water molecules and relative stability of the A- and B-forms of DNA

Accessible surface areas of DNA molecules (A- and B-forms) for different probe particle radii were calculated for poly(dA).poly(dT) and polyd(A-T)].polyd(A-T)] sequences. The problem of different forms stability is discussed in connection with accessible surface area characteristics as well as coulombic interaction between base pairs. The coulombic interaction was shown to play an important role in sequence dependent stability of the DNA molecule.