HYDRATION OF THE DNA BASES IS LOCAL

Ordered hydration sites were determined for the nucleotide bases in B- type conformations using the crystal structure data on 14 B-DNA decame r structures, A method of density representation was extended so that positions, occupancies, and distributions of the hydration sites were predicted around a B-DNA double helix by a method analogous to crystal lographic refinement. The predicted hydration sites correctly reproduc e the main features of hydration around the B-DNA dodecamer. In contra st to the previous observations, the newly available crystal data show the same extent of hydration of guanine and adenine, and of cytosine and thymine.