One unit will hydrolyse 1,0 µmole of o-nitrophenyl-beta-D-galactoside to o-nitrophenol per minute at pH 4,5 and 30 °C.

• Soluble in water
• Insoluble in ethanol, acetone and isopropyl alcohol

Stability: Stable in pH range of 4,0 to 8,0. Stable to heat. Optimum pH is 4,5 and 4,8 when O-Nitrophenyl-beta-D- galactopyranoside and lactose are used as substrate, respectively (Lit.)

Lactase is an enzyme preparation produced by Aspergillus oryzae fermentation. Lactase hydrolyses Lactose (4-o-β-D-Galactopyranosyl-D-glucose) and produces β-D-Galactose and a-D-Glucose.

Lactase is used to screen for blue white colonies in the MCS of various plasmid vectors in Escherichia coli or other bacteria. Its primary commercial use is to break down lactose in milk to make it suitable for people with lactose intolerance.

β-galactosidase cleaves lactose into its monosaccharide components, glucose and galactose. It also catalyses the transglycosylation of glucose into allolactose, the inducer of β-galactosidase, in a feedback loop.