X-ray crystallographic analysis of the hydration of A- and B-form DNA at atomic resolution

We have determined single crystal structures of an A‐DNA decamer and a B‐DNA dodecamer at 0.83 and 0.95 Å, respectively. The resolution of the former is the highest reported thus far for any right‐handed nucleic acid duplex and the quality of the diffraction data allowed determination of the structure with direct methods. The structures reveal unprecedented details of DNA fine structure and hydration; in particular, we have reexamined the overall hydration of A‐ and B‐form DNA, the distribution of water around phosphate groups, and features of the water structure that may underlie the B to A transition. © 2000 John Wiley & Sons, Inc. Biopoly 48: 234–252, 1998