Description
β-galactosidase, also called beta-gal or β-gal, is a hydrolase enzyme that catalyzes the hydrolysis of β-galactosides into monosaccharides. Substrates of different β-galactosidases include ganglioside GM1, lactosylceramides, lactose, and various glycoproteins.
Applications
This enzyme is useful for structural investigation of carbohydrates, the determination of lactose (foodstuff analysis) and as an enzyme label for enzyme immunoassay.
Appearance
White amorphous powder, lyophilized.
Enzyme Commission Number
EC 3.2.1.23
Activity
GradeⅡ 500U/mg-solid or more
Contaminants
α-galactosidase < 1×10⁻⁴% α-glucosidase < 1×10⁻⁴% ß-glucosidase < 2×10⁻³% α-mannosidase < 1×10⁻⁴% ß-mannosidase < 1×10⁻⁴% proteinase < 10mAbs/mg-P
pH Stability
pH 6.5-8.5 (25°C, 20hr)
Michaelis Constant
3.0×10⁻⁴M (o-Nitrophenyl-ß-D-galactoside), 6.7×10⁻⁵M (p-Nitrophenyl-ß-D-galactoside), 2.3×10⁻⁴M (Phenyl-ß-D-galactoside), 2.5×10⁻³M (Lactose)
Structure
The enzyme is composed of four identical subunits having a molecular weight of ca.135,000. The amino acid analysis indicates approximately 1,170 residues per subunit.
Specificity
The enzyme specifically hydrolyzes ß-D-galactosyl linkage
Optimum temperature
50-55°C
Thermal stability
below 50°C (pH 7.3, 15min)
Stability
Stable at-20°C for at least 6 months
Inhibitors
p-Chloromercuribenzoate, lodoacetamide, heavy metal ions (Zn⁺⁺, Fe⁺⁺⁺, Cd⁺⁺, Cu⁺⁺, Pb⁺⁺, Ag⁺, Hg⁺⁺), lonic detergents (SDS, DAC, etc.)
Synonyms
β-galactosidase; beta-gal; β-gal; EC 3.2.1.23; lactase; β-lactosidase; maxilact; hydrolact; β-D-lactosidase; S 2107; lactozym; trilactase; β-D-galactanase; oryzatym; sumiklat; β-D-galactoside galactohydrolase
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