Merck, G4155-5KU, β-Galactosidase from Escherichia coli

General description
Tetramer molecular weight 465 kDa (subunits 116.3 kDa each)
Application
β-Galactosidase is used in the enzymatic assays in the synthesis of imidazolo-pyrrolidinoses.
Biochem/physiol Actions
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.
Physical form
Suspension in 50% glycerol, 5 mM Tris buffer salts, 5 mM magnesium chloride, 0.5 mM DTT, 0.5 mM mercaptoethanol. pH 7.4
Other Notes
Loss of enzymatic activity can occur if this enzyme is frozen. This enzyme is provided in a 50% glycerol solution and will not freeze if stored at -20° Celsius. It is not recommended that this enzyme preparation be stored in an ultracold freezer (-60 to -100° Celsius).
One unit will hydrolyze 1.0 μmole of o-nitrophenyl β-D-galactoside to o-nitrophenol and D-galactose per min at pH 7.3 at 37 °C.