Promotion of Incorporation of Amino-acids by Specific Di- and Tri-nucleotides

Abstract

WHEN disrupted staphylococcal cells are incubated with ¹⁴C-labelled amino-acids and a source of energy, the radioactive amino-acids become incorporated into the protein of the preparation. When only one amino-acid is present in the incubation mixture, incorporation appears to take place by a process of exchange occurring between the added ¹⁴C-labelled amino-acid (or a metabolite thereof) and corresponding residues in the cell protein. In many cases the incorporation can be largely abolished by removal of nucleic acid from the disrupted cells, and then restored by addition of staphylococcal nucleic acid; but the magnitude of these effects varies with the amino-acid the incorporation of which is being studied¹. These differing effects could be explained if the incorporation of specific amino-acids were activated by specific portions within the poly-nucleotide structure, some parts of which were more easily damaged, or replaced, than others.