Instability of the Phosphodiester-Amide Interribonucleotide Bond in Neutral Aqueous Solution

Abstract

Ap(NH₂)dT was synthesized as a model compound for a study of the stability of the phosphodiester-amide interribonucleotide linkage in neutral aqueous solution, by photolyzing A^nBnp(NH₂)dT in anhydrous p-dioxane. Ap(NH₂)dT proved to be unstable even under anhydrous conditions and could not be isolated. It was rapidly decomposed in neutral aqueous buffer solution, at 25°C, to give A>p, dT and ApdT. Three unstable intermediates of this decomposition, A>pNH₂, ApNH₂ and A>pdT were detected by ³¹P NMR. On the basis of the structure of the products, a mechanism is proposed for the decomposition.