SYNTHESIS OF NASCENT PROTEIN BY RIBOSOMES IN ESCHERICHIA COLI

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Abstract
The ribosomes of E. coli can be separated into different sedimentation classes by centrifugation of cell juices through solutions of sucrose. Radioactivity from S35O4 = and C14-amino acids rapidly appears in protein bound to the 70 S and 85 S ribosomes. These become saturated within a few seconds and equally rapidly shed this nascent material as soluble protein which cannot be distinguished from the main bulk of soluble protein. The rate of formation of this nascent protein on the larger ribosomes is adequate to account for the total cell protein synthesis. This process is distinct from the concomitant synthesis of the proteins which constitute the permanent structure of the ribosomes.