CLEAVAGE EFFECT OF OLIGORIBONUCLEOTIDES SUBSTITUTED AT THE CLEAVAGE SITES WITH MODIFIED PYRIMIDINE-NUCLEOSIDES AND PURINE-NUCLEOSIDES

The precursor of an RNA molecule from T4-infected E. coli cells (p2Sp1 RNA) has the capacity to cleave itself at specific positions [UpA (13 9-140) and CpA (170-171)], within a putative loop and stem structure. This sequence-specific cleavage requires at least a monovalent cation and non-ionic detergents. In order to determine the influence of the p yrimidine and purine bases on these sequence-specific cleavage reactio ns, we studied the cleavage reactions of hairpin loop RNAs substituted at the cleavage sites with modified pyrimidine- and purine-nucleoside s. The cleavage was affected by the 2'-hydroxyl groups and the bases o f the pyrimidines, and the 6-amino group of the purine. (C) 1997 Elsev ier Science B.V.