Hydration structures of 2′-deoxyguanosine studied by IR-UV double resonance spectroscopy: comparison with guanosine

Infrared spectra of mono- and dihydrated clusters of 2′-deoxyguanosine (2′-dGs), which are formed by laser desorption combined with supersonic jet-cooling, have been measured by the technique of IR-UV double resonance spectroscopy. The structures of these hydrates are compared with those reported for guanosine (Gs) to elucidate the importance of the 2′-hydroxy group in the hydration. It is shown that monohydrated structures observed for 2′-dGs are similar to those of Gs, indicating no significant influence by the absence of 2′-OH group. For the dihydrated cluster, two structural isomers are identified and assigned to the dihydrates with the guanine moiety is in the keto form, which are consistent with the lowest-energy structures derived from theoretical calculations. Comparison with the results for Gs suggests that the presence of 2′-OH group leads to the stabilization of specific dihydrate structures involving the sugar group.