Theoretical study of the deamination of 1-(2-hydroxy-1-phenylethyl)adenine

In this paper the deamination mechanism of 1-(2-hydroxyl-1-phenylethyl)adenine (HPA) was studied using density functional method. As is known adenine has two possible forms under different pH values. One is the protonated amino form and the other is the neutral imino form. Through our calculations there exist four different mechanisms for the two form HPAs. Among them, pathway d from neutral imino form HPA involving an intramolecular cyclization of 2-hydroxyl-1-phenylethyl side chain is the preferred pathway with lowest energy barriers. In this pathway the hydroxyl group attacks the C6 atom of adenine to produce an oxazolinium intermediate, which is different from the mechanism of adenine deamination. Our calculations demonstrate that unlike other simple 1-alkyladenines, HPA are readily deaminated through intramolecular cyclization due to low energy barrier. In addition HPA occur deamination more easily under neutral condition than under acid condition.