Polypeptide synthesis catalyzed by p-hydroxymercuribenzoate-modified ribosomes.

The stimulation of poly(U)-directed polyphenylalanine synthesis produced by modification of Escherichia coli ribosomes with p-hydroxymercuribenzoate, at low molar ratios of reagent to ribosomes, is due to an increase in the average chain length of polyphenylalanine synthesized, and not to the activation of inactive ribosomes. At a higher molar ratio of p-hydroxymercuribenzoate to ribosomes, which produces no overall change in activity, approximately 50% of the active ribosomes present in the untreated preparation have been completely inactivated, and the remaining active ones, like the ribosomes of the stimulated preparation, synthesize polyphenylalanine at an increased rate as compared with the untreated ribosomes.