ACCUMULATION OF INHIBITORS OF PROTEIN SYNTHESIS AFTER VALINE STARVATION .2. EFFECT ON POLYPHENYLALANINE SYNTHESIS AND BINDING OF PHENYLALANYL TRANSFER RNA

The 105000 × g supernatant from valine-starved cells of Streptococcus faecalis 9790 inhibits the polyuridylic acid-directed synthesis of polyphenylalanine in an Escherichia coli system. The inhibitory fraction affected the binding of phenylalanyl tRNA to Escherichia coli ribosomes. A similarly prepared soluble fraction from exponentially growing cells was not inhibitory. Inhibition of phenylalanyl tRNA binding was not due to ribonuclease activity or to deacylation of the aminoacyl tRNA. Amino acid-starved cell supernatants contained four peaks of inhibitory activity in the basic chromatographic fraction. Two of these chromatographic peaks were present, but in lower level in normal cell supernatants. The inhibitory activity of an isolated peak fraction was destroyed by proteolytic enzymes. © 1969.