SUMMARY: 216 was induced with D-galactose to form galacto-kinase (EC in amounts comparable with those induced in K12. When compared with the basal level, the increase was 20 times greater than in

The greater the concentration of D-galactose, the greater the production of galactokinase in both protoplasts and whole bacteria. In each case the maximum amount of enzyme was induced by 5mM D-galactose. D-Fucose, a gratuitous inducer, produced approximately half the specific activity of enzyme in protoplasts as D-galactose at any particular concentration. The yield of enzyme in the presence of an optimal concentration of D-galactose was increased when the medium was fortified with low concentrations of casein hydrolysate. The specific activities of galactokinase induced in protoplasts and in whole bacteria were respectively 148% and 37% greater in the presence of 0.01% casein hydrolysate.

The maximum specific activity of galactokinase achieved after induction of protoplasts for 60 min. was 3.7 units/mg. protein compared with 12.5 units/ mg. protein in whole bacteria. However, over the first 15 min. after the addition of inducer the same specific activity of galactokinase was achieved in protoplasts as in whole bacteria.


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