Packaging

1000, 3000, 5000, 15000 units in serum bottle

Unit Definition

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.

Physical form

Contains Tris buffer salts and magnesium chloride

Application

β-Galactosidase is conjugated to an antibody which specifically recognizes a target molecule (enzyme immunoassay or EIA).^[1] β-Galactosidase is also used as a reporter enzyme to monitor the level of gene expression of a promoter.^[2] It may be used as a positive control protein with anti-β-galactosidase antibodies.

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.

General description

β-Galactosidase is a tetramer consisting of four equal subunits of 135,000 each. It is a sulfhydryl containing enzyme, with 19 cysteine residues per subunit.^[3]

Physical properties

Tetramer molecular weight 465 kDa (subunits 116.3 kDa each)