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Ab initio modeling of the interaction between guaninecytosine base pair and mustard alkylating agents

TitleAb initio modeling of the interaction between guaninecytosine base pair and mustard alkylating agents
Publication TypeJournal Article
Year of Publication1996
AuthorsBroch H., Hanza A., Vasilescu D.
JournalInternational Journal of Quantum Chemistry
Volume60
Pagination1745-1764
Abstract

Interaction between the guanine-cytosine base pair and the episulfonium form of sulfur mustard (HD+) or the aziridinium form of nitrogen mustard (HN2+) was studied using the ab initio LCAO-MO method at the HF/6-31G level. The alkylation mechanism on the guanine N7 was analyzed by using a supermolecular modeling. Our stereostructural results associated with the molecular electrostatic potentials and highest occupied/lowest unoccupied molecular orbital (HOMO(SINGLEBOND)LUMO) properties show that in vacuum the alkylation of the N7 of guanine by HD+ in the agressive episulfonium form is a direct process without a transition state and of which the pathway is determined. Our study shows that interaction of guanine with the aziridinium form of HN2+ necessitates a transition state for the N7 alkylation route. When the N7 guanine alkylation by HD+ or HN2+ is achieved, about half of a positive charge moves from the alkylator toward the guanine in both cases.

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