INHIBITION BY AMINOCHROMES OF IN VITRO POLYPEPTIDE SYNTHESIS IN ESCHERICHIA COLI

In a previous study of in vitro brain ribosomal protein synthesis from this laboratory, solutions of oxidized catecholamines (aminochromes) were found to inhibit poly U dependent polyphenylalanine synthesis. Since aminochromes also inhibited phenylalanine polymerization in the well defined in vitro ribosomal system from E. coli, the latter was used to determine the effect of aminochromes on various intermediate partial reactions of protein synthesis. All of the partial reactions studied were inhibited by approximately 50% at aminochrome concentrations of 3-5 × 10-4m (10 times that required for equivalent inhibition of overall polymerization). In addition, using Sephadex G-50 and G-100 chromatography, it was determined that high molecular weight oxidized products from epinephrine (melanin precursors) are bound to ribosomes, and this may explain the observed inhibition. © 1969.