Lactose metabolism

Lactose enters the E. coli cell from the growth medium with the aid of permease. Most of the lactose has its galactoside linkage cleaved by-galactosidase to yield galactose and glucose. -galactosidase converts some lactose to its isomeric form, allolactose that acts as the inducer. Excess allolactose is cleaved by -galactosidaseLactose enters the E. coli cell from the growth medium with the aid of permease. Most of the lactose has its galactoside linkage cleaved by-galactosidase to yield galactose and glucose. -galactosidase converts some lactose to its isomeric form, allolactose that acts as the inducer. Excess allolactose is cleaved by -galactosidase

H OHI |H OH Galactoside linkage Lactose Allolactos: 0 B-galactosidase CH CH CH CH 0 OH 0 OH OH Galactose GlucoseH