ABSTRACT
RNA In RNA, the same denaturation of helical regions will take place at higher pH, but this effect is overshadowed by the susceptibility of RNA to hydrolysis in
alkali. This comes about because of the presence of the 2-OH group in RNA, which is perfectly positioned to participate in the cleavage of the RNA backbone by intramolecular attack on the phosphate of the phosphodiester bond (Fig. 2). This reaction is promoted by high pH, since −OH acts as a general base. The products are a free 5-OH and a 2,3-cyclic phosphodiester, which is subsequently hydrolyzed to either the 2- or 3-monophosphate. Even at neutral pH, RNA is much more susceptible to hydrolysis than DNA, which of course lacks the 2-OH. This is a plausible reason why DNA may have evolved to incorporate 2-deoxyribose, since its function requires extremely high stability.
