Inhibition of the initial dipeptide synthesis of globin chains by the antibiotic enomycin in the reticulocyte lysate.

Abstract

During inhibition of protein synthesis by the antitumor antibiotic enomycin at less than 5 nm in a reticulocyte lysate system, polyribosomes disaggregated and 80S ribosomes accumulated. At these concentrations little inhibition of chain elongation and release from the ribosomes was demonstrated. Enomycin caused an increase in the amount of 80S initiation complex and the 40S ribosomal subunit-Met-tRNAf complex. The former complex could react with puromycin under the inhibiting conditions. Val-tRNA binding to 80S ribosomes was not decreased by the antibiotic. Pactamycin-induced accumulation of the initial dipeptide (fMet-Val) was inhibited when the system was preincubated with enomycin and fMet-tRNAf. The preferential inhibition of the initial phase of protein synthesis by enomycin is evident by its inhibition of initial dipeptide synthesis.