A comparative study on the cleavage of stereoisomeric uridylyl(3',5')uridines [D,D-, D,L- and L,D-UpU] by acid, base and metal ion catalysts.

Stereoisomeric uridylyl(3',5')uridines D,L-UpU and L,D-UpU were synthesised. Their cleavage was followed in the presence of acid, base and metal ion catalysts to study whether the stereochemistry affects the inherent reactivity of the internucleosidic phosphodiester bond, and whether the low molecular weight catalysts can distinguish between the substrates. The rate constants obtained were compared to those of D,D-UpU. The comparison shows that the stability of the phosphodiester bond does not depend on the stereochemistry of the sugar rings. In contrast slight reactivity differences are observed in the presence of metal ion catalysts, which suggests that selective cleavage of stereoisomeric substrates even by small molecular weight chemical catalysts may be possible.