Abstract
Incubation of Escherichia coli 15T- in the presence of puromycin inhibits the inducible formation of β-galactosidase to a greater extent than it inhibits protein synthesis. In E. coli 33.00 β-galactosidase formation is also more sensitive to the presence of puromycin than is protein synthesis. In the presence of glycerol (but not in its absence) puromycin prevents the production of messenger RNA for β-galactosidase, presumably as a result of catabolite repression.