Sequence-dependent hydration water dynamics of dodecameric DNA

Nakagawa, Hiroshi   ; Yonetani, Yoshiteru*; Nakajima, Kenji  ; Kawamura, Seiko   ; Kikuchi, Tatsuya*  ; Inamura, Yasuhiro  ; Kataoka, Mikio*; Kono, Hidetoshi*

Hydration water dynamics were measured by quasi-elastic neutron scattering with HnO/DO contrast for two DNA dodecamers, 5'CGCGCGCG'3 and 5'CGCGCGCG'3, which have been computationally shown to be structurally rigid and flexible, respectively. The dynamical transitions of the hydration water as well as DNA were observed for both sequences at approximately 240 K. Above the transition temperature, the mean square displacements of the hydration water for the rigid sequence were smaller than those for the flexible one. Furthermore, the relaxation time of the hydration water was longer in the rigid DNA than in the flexible DNA. We suggest that hydration water dynamics on the picosecond timescale are associated with sequence-dependent deformability of DNA.