The Deamination Mechanism Of The 5,6-Dihydro-6-Hydro-6-Hydroxylcytosine And 5,6-Dihydro-5-Methyl-6-Hydroxylcytosine Under Typical Bisulfite Conditions

The hydrolytic deamination of HOHCytN3(+) (paths A and B), and 5-HOHMeCytN3(+) (paths C and D) have been explored in the presence of the group. The activation free energy barriers (Delta G(s not equal)) of paths A and C show significant difference, which increases the possibility in differentiating cytosine (Cyt) from 5-methylcytosine (5-MeCyt) under bisulfite conditions. Meanwhile, the calculated rate constants with Wigner tunnelling correction of the rate-limiting step is much lower for path A than for path C, and by extrapolation, the difference between Cyt and 5-MeCyt for both modified pyrimidine base may have a greater chance by bisulfite treatment.[GRAPHICS].