The effect of chlortetracycline on the transfer of leucine and ‘transfer’ ribonucleic acid to rat-liver ribosomes in vitro

Chlortetracycline prevents the passage of leucine from 'transfer' RNA to ribosomal protein in cell- free preparations from E8cherichia coli and rat liver; the leucine is largely retained on the 'transfer' RNA (Franklin, 1963). Since attachment of 'transfer' RNA to ribosomal RNA may occur inde- pendently of amino acid incorporation into protein (Bloemendal & Bosch, 1962), it was decided to determine whether chlortetracycline prevents attachment of the amino acyl-'transfer' RNA to the ribosome or whether it prevents the subsequent condensation of amino acids into polypeptides. The present paper describes experiments with rat- liver preparations. METHODS Radioactive chemicals. Generally labelled L-leucine (L-[G-14C]leucine) (24-8 mc/m-mole) and [6-14C]orotic acid (11l6 mc/m-mole) were obtained from The Radiochemical Centre, Amersham, Bucks. Chemicals. The sodium salt of ATP, the silver-barium salt of phosphoenolpyruvic acid, pyruvate kinase and pan- creatic ribonuclease were obtained from C. F. Boehringer und Soehne G.m.b.H., Mannheim, Germany. The sodium salt of GTP was obtained from Pabst Laboratories,