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.
β-Galactosidase is used in the enzymatic assays in the synthesis of imidazolo-pyrrolidinoses.
β-Galactosidase may be used for derivatization, such as an enzyme label for IgG, without prior dialysis or gel filtration.
β-galactosidase was used in the production of a stabilized, single reagent for alcohol analysis.
β-Galactosidase was used for reversed-phase (RP) adsorption. 1 It was also used in the hydrolysis of whey lactose.
β-Galactosidase from bovine testes was used for coupling to Sepharose.
ChEBI: Beta-D-galactose is a D-galactopyranose having beta-configuration at the anomeric centre. It has a role as an epitope and a mouse metabolite. It is an enantiomer of a beta-L-galactose.
Replagal (Transkaryotic Therapies).
Biotechnological Production
b-D-Galactosidase (b-D-galactoside galactohydrolase, EC 3.2.1.23) hydrolyses the
glycosidic bond of the disaccharide lactose into its monomers glucose and galactose.
Therefore, b-D-galactosidase is also known as lactase. b-D-Galactosidases
can be found throughout nature. Commercial enzymes are mainly of fungal origin
of the genera Kluyveromyces (yeast) and Aspergillus (filamentous ascomycete). Although several b-D-galactosidases are available on the market, new efforts
are still conducted to improve the enzymatic properties by site-directed mutagenesis or to find new b-D-galactosidase genes by screening metagenome databases.
From a technological point of view, the milk sugar lactose is hydrolyzed
because of the resulting increase of sweetness and the reduced susceptibility to
crystallization during spray drying of milk and whey. Nevertheless, the
most apparent application is the production of ‘‘lactose-free’’ milk products, which
enables the consumption of dairy products by lactose-intolerant people.
For industrial processes, b-D-galactosidases can be applied by immobilization
of the enzyme on carriers, such as cellulose, alginate, or other polymers, for
hydrolysis of milk or whey products. Conversion rates of lactose in batch and
continuous operation mode by immobilized b-D-galactosidase might reach 95 %. To reach even lower lactose concentrations of less than 0.01 %, a combination
of b-D-galactosidase activity and ultrafiltration as well as nanofiltration
methods can be used. Besides the degradation of substances that lead to food
intolerances, the elimination of food allergens by means of a specific degradation
of allergenic epitopes is another promising application of enzymes.
The GLB1 (β-Galactosidase) gene is mapped to human chromosome 3p22.3. The encoded protein belongs to glycosyl hydrolase 35 family and is localized to lysosomes.
Releases β(1→3)- and β(1→6)-linked galactose from the non-reducing end of complex oligosaccharides.
It is purified 600-fold by (NH4)2SO4 precipitation, acetone fractionation and affinity chromatography on agarose substituted with terminal thio-.-galactopyranosyl residues. [Distlern & Jourdian J Biol Chem 248 6772 1973.]
