Comparison of alkyl group labilities in O-and N-alkylated DNA bases: A semiempirical molecular orbital study
All O-alkylated DNA bases and nucleosides possess alkyl groups considerably more labile than those in N-alkylated bases and nucleosides, being prone to degradation through loss of the alkyl group at strongly acidicpH. The strength of the bond between the alkyl group and the atom on the base to which it is bound is calculated here using the semiempirical INDO-SCF-MO method, comparison being made between O6-alkylguanines, O4-alkylthymines and N7-alkylguanines. The results, calculated for many different alkyl groups, predict that the strength of this bond at acidicpH would be appreciably lower for the O-alkylated bases than for the N7-alkylguanines, but that increase ofpH would serve to stabilise this bond for the O-alkylated bases. These predictions are in good accord with experimental findings.
Volume 134, 2022
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