• G4155
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β-Galactosidase from Escherichia coli

aqueous glycerol suspension, ≥500 units/mg protein (biuret)

β-D-Galactoside galactohydrolase, Lactase
CAS Number:
Enzyme Commission number:
MDL number:


aqueous glycerol suspension

Quality Level

specific activity

≥500 units/mg protein (biuret)

mol wt

465 kDa

storage temp.


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β-Galactosidase is used in the enzymatic assays in the synthesis of imidazolo-pyrrolidinoses.


1000, 3000, 5000 units in glass bottle

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 properties

Tetramer molecular weight 465 kDa (subunits 116.3 kDa each)

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

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).

Storage Class Code

10 - Combustible liquids



Flash Point(F)

Not applicable

Flash Point(C)

Not applicable

Certificate of Analysis

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Certificate of Origin

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Technical Information

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