Relationship between cell-free synthesis of ornithine transcarbamylase and protein synthesis

An increase in ornithine transcarbamylase activity, observed in a cell-free system derived from Escherichia coli, has been examined with the following results: (1) The increase in enzyme activity required particles, ATP, and GTP and was inhibited by chloramphenicol and ribonuclease. (2) The E. coli W system was inhibited by arginine and UTP, and the supernatant from E. coli W cells grown in arginine did not support increase in ornithine transcarbamylase activity. (3) The extent and duration of enzyme activity increase was greater when s-RNA, RNA polymerase, and DNA were added to dialyzed supernatants and washed particles of E. coli B (R −). (4) Partial purification of the enzyme after in vitro incubation demonstrated that ornithine transcarbamylase was −C 14 formed by the cell-free system from E. coli. (5) Calculation revealed that only 1% of the increase in enzyme activity observed could be accounted for by incorporation of C 14-amino acids into ornithine transcarbamylase-C 14. Rather than demonstrating complete de novo synthesis of new enzyme protein, the results suggested a cell-free completion of protein chains resulting in active enzyme formation.