Presence of Low Molecular Weight Inhibitors of Protein Synthesis in the Developing Embryo 1

Abstract

Summary

Low molecular weight substances isolated from 8-day-old chick embryos inhibited incorporation of lysine and isoleucine into TCA-precipitable protein. One of these, moreover, blocked the uptake of uridine into nucleic acid.

They were heat stable and dialyzable. Inhibitor I had an approximate mol wt of 600-700; II had an approximate mol wt of 450; III was under 500. Treatment with RNAse, DNAse, trypsin and pronase did not result in loss of activity of the inhibitors. None of the inhibitors manifested proteolytic activity.