Metastable fragmentation of a thymidine-nucleotide and its components

► Metastable decay of thymine nucleotides are characterized by N-glycosidic, phosphoester and nucleobase ring cleavage. ► The initial deprotonation position determines the specific reaction pathway. ► Sugar cross-ring cleavage is only relevant for small DNA subunits. ► Formation of NCO− from thymine is due to deprotonation of N3. ► Presence of the phosphate group dominates fragmentation since it carries the negative charge.