Native E. coli beta Galactosidase protein (ab7981)



  • Nature
  • Source
    Escherichia coli
  • Amino Acid Sequence
    • Species
      Escherichia coli
    • Molecular weight
      465 kDa
    • Additional sequence information
      Beta Galactosidase is a homotetramer with a molecular weight of 465.4 kDa (116.3 kDa subunits each).


Our Abpromise guarantee covers the use of ab7981 in the following tested applications.

The application notes include recommended starting dilutions; optimal dilutions/concentrations should be determined by the end user.

  • Biological activity

    One Unit hydrolyzes one micromole of o-nitrophenyl-β-D-galactopyranoside per minute at 25°C, pH 7.5.

    Activity: ≥50 units per mg dry weight.

    Optimum pH range of 6 to 8.


  • Form
  • Concentration information loading...

Preparation and Storage

  • Stability and Storage

    Shipped at 4°C. Store at +4°C.

    This product is an active protein and may elicit a biological response in vivo, handle with caution.

  • Reconstitution
    Reconstitute in 0.1 M Sodium/potassium phosphate, pH 7.0.

General Info

  • Alternative names
    • Beta D galactosidase
    • Beta gal
    • Beta galactosidase
    • ECK0341
    • JW0335
    • Lactase
    • lacZ
    see all
  • Relevance
    Beta galactosidase is coded by a gene (lac z) in the lac operon of Escherichia coli. It is a metalloenzyme that splits lactose into glucose and galactose. It hydrolyzes terminal, non-reducing beta-D-galactose residues in beta-D-galactosides. Activation by cations seems to be substrate dependent. K+, Na+, NH4+, Rb+, Cs+ and Mn++ all activate enzyme activity based upon the substrate used.
  • Cellular localization


ab7981 has not yet been referenced specifically in any publications.

Customer reviews and Q&As


It is an active protein, the assay we use to determine activity is Beta galactosidase assay. We have not sequenced this product but it is sourced from E coli and should be similar to P00722 (

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Thank you for your enquiry and interest in our products.

I can confirm that these two products (ab7981 and ab79449) are not His-tagged. I have checked our catalogue and currently we only sell non-tagged beta Galactosidase protein.


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Thank you for contacting Abcam earlier today.

For lot * there are 165 u/mgDW (dry weight) in this lot.

If there is anything else I can help you with, please let me know.

Thank you for contacting us yesterday.

I am sorry to hear you are experiencing difficulties with one of our products. As discussed over the phone, I'd like to try and help you to improve the results currently obtained. In order to do this, c...

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Thank you for your call today and for your question about ab7981.

The buffer recommended for reconstitution is based on the assay described in the following reference:

Craven et al. (JBC, 240, 2468,1965)

The buffer is 0.1 ...

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Thank you for contacting us. The current lot we have in stock, GR20915-2, has 51.0 units activity per milligram dry weight, so you should receive 98 mg. Other lots will vary in the unit activity per milligram. We suggest reconstituting at a min...

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Thank you for your inquiry. I am afraid that these products, ab7981 and ab79449, does not contain a His tag. If there is anything else that I can help you with, please do not hesitate to contact me.


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