Intermolecular interactions between nucleoside, amino acid, and water molecules probed by ultraviolet photodissociation in the gas phase

Abstract

The effects of intermolecular interactions on the reactivity of hydrogen-bonded clusters of adenosine and tryptophan (Trp) in the gas phase were investigated by water adsorption and ultraviolet photoexcitation. The product ion spectra of photoexcited H+(Trp)(adenosine) and its hydrated clusters were obtained at 8 K using a tandem mass spectrometer equipped with an electrospray ionization source and a cold ion trap. The primary product ion of photoexcitated H+(Trp)(adenosine) was H+(adenine), which was formed via Trp detachment and glycosidic bond cleavage of adenosine. The primary product ion formed after the photoexcitation of H+(Trp)(adenosine)(H2O)n was H+(adenosine), which resulted from the detachment of Trp and water molecules. The relative abundance of H+(adenosine) was substantially higher than that of H+(adenine), indicating that water adsorption on H+(Trp)(adenosine) weakened the intermolecular interactions between Trp and adenosine and inhibited the photoinduced glycosidic bond cleavage of adenosine in the clusters.