SYNTHETIC POLYNUCLEOTIDES AND THE AMINO ACID CODE. VI

Abstract

Polymers prepared with polynucleotide phosphorylase by priming the synthesis of poly U with a mixture of oligoribonucleotides containing ApU and ApApU, promoted the incorporation of phenylalanine and small amounts of tyrosine by the cell-free E. coli system. The polymers had no effect on the incorporation of isoleucine, asparagine, and lysine. In contrast, random poly UA stimulated the incorporation of isoleucine and tyrosine to the same extent. Since the base composition of the triplet code letters for tyrosine or isoleucine is 2U1A, the results suggest that tyrosine incorporation may be caused by a beginning AUU sequence in the primed polymers.