Instability of Puromycin

Abstract

PUROMYCIN dihydrochloride is being extensively used as an inhibitor of protein synthesis. This antibiotic inhibitor is valuable because its mode of action on protein biosynthesis has been elucidated in precise molecular terms¹. Examination of the literature shows, however, that there is a considerable range in the reported potencies of different samples of the inhibitor. For example, Wheelock found that 10⁻⁴ M (about 50 µg/ml.) puromycin completely inhibited protein synthesis in HeLa cells within 45 min of treatment², while Shah's data, also on HeLa cells, show that twice that amount of puromycin (100 µg/ml.) allowed protein synthesis to take place at 20 per cent of the control rate after 6 h of puromycin action³. Numerous other examples of such discrepancies can be found^4–7. This communication draws attention to the fact that different batches of the compound may vary in potency.