Effect of nucleotide substitution on the peptidyltransferase activity of 2'(3')-O-(aminoacyl) oligonucleotides.

Seven 2'(3')-O-(aminoacyl) trinucleotides with structures derived from the 3'-terminal C-C-A sequence of aa-tRNA via nucleotide substitutions were investigated as acceptor substrates in the peptidyltransferase reaction and as inhibitors of substrate binding to the peptidyltransferase A site. It was found that all tested compounds were active in both systems, although substitution in the first and second nucleotide position results in some decrease of acceptor activity. Remarkably, replacement of natural cytidylic acid residues in C-C-A-Phe with guanylic acid moieties resulted only in a small decrease of acceptor or binding activity. The results indicate that the acceptor sequence of aa-tRNA is not probably engaged in base pairing with a sequence of 23S RNA during its interaction with the peptidyltransferase A site.