Effects of electron attachment on C5'-O5' and C1'-N1 bond cleavages of pyrimidine nucleotides: A theoretical study.
Sugar-base C(1')-N(1) and phosphate-sugar C(5')-O(5') bond breakings of 2'-deoxycytidine-5'-monophosphates (dCMP) and 2'-deoxythymidine-5'- monophosphates (dTMP) and their radical anions have been explored theoretically at the B3LYP/DZP++ level of theory. Calculations show that the low-energy electrons attachment to the pyrimidine nucleotides results in remarkable structural and chemical bonding changes. Predicted Gibbs free energies of reaction DeltaG for the C(5')-O(5') bond dissociation process of the radical anions are -14.6 and -11.5 kcal mol(-1), respectively, and such dissociation processes may be intrinsically spontaneous in the gas phase. Furthermore, the C(5')-O(5') bond cleavage processes of the anionic dCMP and dTMP were predicted to have activation energies of 6.9 and 8.0 kcal mol(-1) in the gas phase, respectively, much lower than the barriers for the C(1')-N(1) bond breaking process, showing that the C-O bond dissociation in DNA single strand breaks is a dominant process as observed experimentally.
Xie
Hujun
H
Department of Chemistry and State Key Laboratory of Physical Chemistry of Solid Surfaces, Xiamen University, Xiamen 361005, China.
Wu
Ruibo
R
Xia
Fei
F
Cao
Zexing
Z
D053904:DNA Breaks, Single-Stranded; D004583:Electrons; D008956:Models, Chemical; D008962:Models, Theoretical; D015394:Molecular Structure; D011742:Pyrimidine Nucleotides / Q000737:chemistry*
D011742:Pyrimidine Nucleotides