Sequence effect on the slow degradations of dinucleotides by fast atom bombardment tandem mass spectrometry.

The mass-analysed ion kinetic energy spectrum of isomeric dinucleotides having dTpdU and dUpdT structure is characterized by the preferred elimination of the pyrimidine base linked to the 5' end deoxyribose unit. Similar results have been obtained with differently substituted dimers such as dCpdT and DMTdTp(S)dU. The observed selectivity in the glycosidic bond dissociation provides a straightforward criterion for the sequencing of the sampled species.