F. keratolyticus Endo-beta-Galactosidase Protein, CF

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R&D Systems Recombinant Proteins and Enzymes
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F. keratolyticus Endo-beta-Galactosidase Protein, CF Summary

Learn more about Fluorescent Glycan Labeling and Detection

Product Specifications

>95%, by SDS-PAGE visualized with Silver Staining and quantitative densitometry by Coomassie® Blue Staining.
Endotoxin Level
<1.0 EU per 1 μg of the protein by the LAL method.
Measured by its ability to cleave keratan sulfate. 50% cleavage of keratan sulfate (0.5 μg) is achieved using <5 ng rF.k. Endo-beta -galactosidase, as measured under the described conditions. 
E. coli-derived f. keratoyticus Endo-beta-Galactosidase protein
Accession # P25738
GSENLYFQGHMHHHHHH F. keratolyticus Endo-beta -Galactosidase (Asp25-Leu422) Accession # Q9ZG90
N-terminal Sequence
Thr2 (msyB)
Predicted Molecular Mass
59 kDa
66 kDa, reducing conditions

Product Datasheets

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Carrier Free

What does CF mean?

CF stands for Carrier Free (CF). We typically add Bovine Serum Albumin (BSA) as a carrier protein to our recombinant proteins. Adding a carrier protein enhances protein stability, increases shelf-life, and allows the recombinant protein to be stored at a more dilute concentration. The carrier free version does not contain BSA.

What formulation is right for me?

In general, we advise purchasing the recombinant protein with BSA for use in cell or tissue culture, or as an ELISA standard. In contrast, the carrier free protein is recommended for applications, in which the presence of BSA could interfere.


Formulation Supplied as a 0.2 μm filtered solution in Tris and NaCl.
Shipping The product is shipped with polar packs. Upon receipt, store it immediately at the temperature recommended below.
Stability & Storage: Use a manual defrost freezer and avoid repeated freeze-thaw cycles.
  • 6 months from date of receipt, -20 to -70 °C as supplied.
  • 3 months, -20 to -70 °C under sterile conditions after opening.

Assay Procedure

  • Labeling Buffer: 25 mM MES, 0.5% (v/v) Triton® X-100, 2.5 mM MgCl2, 2.5 mM MnCl2, 1.25 mM CaCl2, 0.75 mg/mL BSA, pH 7.0
  • Assay Buffer: 0.1 M MES, pH 6.0
  • Gel Running Buffer: 40 mM Tris, 1 mM EDTA, adjust to pH 8.0 with acetic acid
  • Recombinant F. keratoyticus Endo-beta -Galactosidase (rF.k. Endo-beta -galactosidase) (Catalog # 8620-GH)
  • Goat Keratan Sulfate Proteoglycans (Catalog # 8618-KS)
  • Recombinant Human Carbohydrate Sulfotransferase 1/CHST1 (rhCHST1) (Catalog # 5316-ST)
  • 8% SDS-PAGE (approximately 15 cm x 20 cm, 20 lanes per gel)
  • PAP35S (prepared in-house using the PAPS Synthesis Kit (Catalog # EA005), ~1 μM  = ~2 x 106 cpm/μL)
  • Gel loading buffer: 0.15 M Tris, 20.8 mM SDS, 1.15 M Glycine, 174 µM Bromophenol Blue, 30% Glycerol 
  • Blotting paper (Fisher Scientific, Catalog # 05-714-4)
  • Gel dryer
  • Glogos® II autorad markers (Stratagene, Catalog # 420202) or equivalent
  • Blue sensitive medical X-ray film
  • X-ray film cassette
  • Film developer (Konica SRX-101A Medical Film Processor) or equivalent
  • Liquid scintillation counter (Beckman Coulter, Model # LS5000TD) or equivalent
  • Liquid scintillation fluid (Beckman Coulter, Catalog # 141349) or equivalent
  1. Create Radiolabeled Keratan Sulfate Mixture containing 0.1 mg/mL Keratan Sulfate, 12 μg/mL rhCHST- 1, and 0.025 μM PAP35S in Labeling Buffer.
  2. Incubate Keratan Sulfate Mixture at 37 °C for 1.5 hours.
  3. Dilute incubated Keratan Sulfate Mixture 3 fold in Assay Buffer.
  4. Dilute rF.k. endo-beta -galactosidase to 2.667, 0.667, 0.2667, 0.133, 0.0667, 0.02, 0.00667, and 0.00133 µg/mL in Assay Buffer.
  5. Combine 15 µL of rF.k. endo-beta -galactosidase at each dilution with 15 µL diluted Keratan Sulfate Mixture. Include a control containing 15 µL Assay Buffer and 15 µL Keratan Sulfate Mixture.
  6. Incubate all reactions at 37 °C for 20 minutes.
  7. Add 15 µL gel loading buffer to each reaction. Mix.
  8. Load 30 µL of each reaction per lane on a gel. Leave empty lanes between samples.
  9. Run at 200 V for 30 minutes.
  10. Transfer gel onto blotting paper and dry with gel dryer for 1 hour or until fully dry.
  11. Affix two autorad markers to the blotting paper next to the dried gel.
  12. In a darkroom expose dried gel to X-ray film by enclosing overnight in a cassette. Develop the following day.
  13. Using the dried gel, begin marking regions to be cut out for scintillation counting.
  14. Mark a horizontal line across the top of the entire gel just under the bottom of the wells.
  15. Using the developed film as an overlay, mark a second line just below the lower edge of the labeled Keratan Sulfate for each well.
  16. Draw a third line just below where the labeled product migrated (ignore any free sulfate, appearing equivalent in all lanes, and migrating the furthest). For the control, identify the empty region where the product would appear.
  17. The area between the first two lines is considered to contain the labeled starting material. The area between the second two lines is considered to contain the compact cleavage product resulting from the reaction.
  18. Mark vertical lines distinguishing one lane (reaction condition) from another.
  19. Cut each region (two per lane) and place each into a separate liquid scintillation vial. Add 5 mL liquid scintillation fluid to each vial and count the vials for 35S.
  20. Determine the amount of rF.k. Endo-beta -galactosidase required for 50% cleavage by plotting % cleavage vs. ng of
    rF.k. Endo-beta -galactosidase with 4-PL fitting.

Per Reaction:
  • Keratan Sulfate: 0.5 μg
  • rF.k. Endo-beta -galactosidase: 40, 10, 4, 2, 1, 0.3, 0.1 and 0.02 ng
Reconstitution Calculator

Reconstitution Calculator

The reconstitution calculator allows you to quickly calculate the volume of a reagent to reconstitute your vial. Simply enter the mass of reagent and the target concentration and the calculator will determine the rest.


Background: Endo-beta-Galactosidase

F. keratolyticus Endo-beta -Galactosidase hydrolyzes internal beta (1-4) galactose linkages in poly-N-acetyllactosamine [GlcNAc beta (1-3)Gal beta (1-4)] structures as well as sulfated structures such as keratan sulfate (1). It has wider substrate specificity and work more efficiently than its counterparts from E. freundii and B. fragilis (2). The enzyme may be used in fractional protein isolation (3). It may also be used for deglycosylation (4). Branching and/or fucosylation of the substrate may reduce or inhibit cleavage.

  1. Leng, L. et al. (1998) Gene 222:187.
  2. Amano. J. et al. (1991) J. Biol. Chem. 266:11461.
  3. Maria Vistnes et al. (2014) PLoS ONE 9:e89621
  4. Xiaoke Yin et al. (2013) Molecular & Cellular Proteomics 12:956.
Alternate Names


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F. keratolyticus Endo-beta-Galactosidase Protein, CF
By Anonymous on 01/15/2020
Application: Mass spectrometry analysis of N-glycan structures
Reason for Rating: This product is compatible for digestion of N-glycans for downstream mass spectrometry analysis.