Abstract. β-Galactosidase (Escherichia coli) is a tetrameric enzyme of historical and scientific importance that is used in several molecular biology applications. The natural substrate of the enzyme is lactose. It is converted to either galactose and glucose (hydrolysis) or allolactose (galactosyl transfer).

Is beta-galactosidase A constitutive enzyme?

constitutive enzyme An enzyme that is always produced whether or not a suitable substrate is present. ... An example is the lac-operon, which controls the synthesis of three enzymes (beta-galactosidase, permease, and acetylase): enzymes that are involved in the lactose metabolism of the bacterium Escherichia coli.

What is the specific activity of beta-galactosidase?

β-Galactosidase has three enzymatic activities (Fig. 1). First, it can cleave the disaccharide lactose to form glucose and galactose, which can then enter glycolysis. Second, the enzyme can catalyze the transgalactosylation of lactose to allolactose, and, third, the allolactose can be cleaved to the monosaccharides.