Changes in the specific activities of the galactose enzymes in E. coli under different growth conditions

Summary An increase in the specific activity of kinase and transferase is observed when late growth phase is compared with early exponential phase. The increase is more pronounced in the presence of saturating inducer concentrations than in uninduced cultures. Epimerase does not increase in late growth phase in the presence of D-fucose, provided the other enzymes of the galactose pathway are present. It is believed that increases observed are due to an increased rate of synthesis of the galactose enzymes in late growth phase, and that the lack of coordination found for epimerase is due to an inactivation of the latter enzyme, which occurs in the presence of D-fucose and needs an intact galactose pathway.