INHIBITION BY PUROMYCIN OF AMINO ACID INCORPORATION INTO PROTEIN

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Abstract
Structural similarities between the broad-spectrum antibiotic puromycin (6-dimethylamine-9-[3''-deoxy-3''-(p-methoxy-L-phenylalanylamine)-[beta]-D-ribofuranosyl]purine) and the amino acid-bearing end of S-ribonucleic acid (RNA) are discussed. Puromycin was found to inhibit the incorporation of leucine-C14 into protein in a cell-free preparation from rat liver. Puromycin does not inhibit the rate of ATP (adenosine triphosphate)-generation by either of 2 enzyme systems used in the leucine incorporation experiments. It does not inhibit the rate of leucine activation by the "pH 5 fraction" of rat liver. No puromycin inhibition of the extent of S-RNA labeling with leucine-C14 could be detected. The transfer of leucine-C14 from S-RNA-leucine-C14 to protein is inhibited by puromycin. The extent of this inhibition is considered sufficient to account for the inhibition by puromycin of leucine incorporation into protein. Observations of other workers which suggest a similar site of action for the antibiotics chloramphenicol and dihydrostreptomycin are briefly discussed.
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