Theoretical Investigation on Tautomerization Mechanism of 6-Thioguanine

Abstract:

The tautomerization reaction mechanisms between three stable 6-thioguanine tautomers were investigated theoretically using B3LYP/6-311+G(d,p) method. The results show that the pathway P(1) is to isomerize from TG(9,10,10,11) to TG(1,9,10,10) and the needed activation Gibbs free energy barrier is 112.7 kJ/mol with the rate constant of 1.12×10^-7 s^-1. Another two pathways P(2) and P(3) are to isomerize from TG(1,9,10,10) to TG(1,7,10,10) and the activation Gibbs free energy barriers of the rate-determining steps are 227.4 and 281.6 kJ/mol, respectively, with the related rate constants of 8.96×10^-28 s^-1 and 2.86×10^-37 s^-1, these results implying the intramolecular proton transfer reactions are infeasible in the gas phase.

• Periodical: Advanced Materials Research (Volumes 690-693)
• Pages: 1418-1421
• DOI: https://doi.org/10.4028/www.scientific.net/AMR.690-693.1418
• Online since: May 2013
• Authors: Hong Jiang Ren
• Keywords: 6-Thioguanine, Activation Gibbs Free Energy Barrier, Tautomerization

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