A high-angle neutron fibre diffraction study of the hydration of B-DNA

A high-angle neutron fibre diffraction study of hydration in the B conformation of DNA has been performed on instrument D19 at the Institut Laue-Langevin, Grenoble, using a sample prepared by the 'wet spinning' technique. In common with our previous neutron fibre diffraction studies, this work exploited the ability to isotopically replace H₂O in the specimen by D₂O. However, in contrast to previous studies, the sample exhibited 'double orientation' so that it was possible to record a three-dimensional diffraction data set. Fourier synthesis techniques were used to image ordered water surrounding the DNA. Two chains of ordered water were identified in the minor groove of the molecule in positions that are consistent with water bridging of sugar O4 and purine N3 or pyrimidine O2 atoms.