Detection of the peptidyltransferase activity of a dipeptide, alanylhistidine, in the absence of ribosomes.

It was shown that a dipeptide, alanylhistidine, can act as a catalyst for the peptidyl transfer reaction in the absence of ribosomes between the amino acid moieties of phenylalanyl, lysyl, prolyl, and glycyl tRNAs depending on their model templates, poly U, poly A, poly C, and poly G, respectively. A template effect was observed: The peptidyl transfer reaction between tRNAGly molecules (anticodon GCC) occurred in the presence of poly G but not in the presence of poly C. The reaction was most efficient for the best stacked poly A (tRNALys) and least efficient for the worst stacked poly U (tRNAPhe).