Enzymatic Assay of ß-Glucuronidase (EC from Helix Pomatia and Bovine Liver

1. Objective

To standardize a procedure for Enzymatic Assay of b-Glucuronidase1 at Sigma-Aldrich St. Louis.

2. Scope

This procedure applies to all b-Glucuronidase products that are derived from Helix Pomatia and Bovine Liver.

3. Definitions

One Sigma or modified "Fishman" unit will liberate 1.0 microgram of Phenolphthalein from Phenolphthalein Glucuronide per hour at pH 5.0 at 37°C.

4. Discussion

PheP-Gluc + H2O   b-Glucuronidase   >D-Glucuronate + Phenolphthalein

PheP-Gluc = Phenolphthalein Glucuronide

5. Responsibilities

It is the responsibility of trained Analytical Services laboratory personnel to follow this procedure as written.

6. Safety

Refer to Safety Data Sheets (SDS) for hazards and appropriate handling precautions.

7. Procedure

T = 30°C, pH = 5.0, A540nm, Light path = 1 cm

Spectrophotometric Stop Rate Determination


7.3.1    100 mM Sodium Acetate Buffer, pH 5.0 at 37°C
(Prepare 50 ml in deionized water using Sodium Acetate, Trihydrate, Sigma-Aldrich Product Number S8625 . Adjust to pH 5.0 at 37°C with 1 M HCl.)

7.3.2    1.2 mM Phenolphthalein Glucuronide Substrate Solution (PheP-Gluc)
(Prepare by diluting 1 ml of Phenolphthalein Glucuronic Acid, Sigma Stock Number 105-4, with 8 ml of deionized water.)

7.3.3    200 mM Glycine Buffer Solution, pH 10.4
(Prepare 100 ml in deionized water using Glycine Free Base,Sigma Product Number G7126. Adjust to pH 10.4 at 37°C with 1 M NaOH.)

7.3.4    0.2% (w/v) Sodium Chloride Solution (NaCl)
(Prepare 20 ml in deionized water using Sodium Chloride, Sigma-Aldrich Product Number S9888 .)

7.3.5    b-Glucuronidase Enzyme Solution
(Immediately before use, prepare a solution containing 250-500 units/ml of b-Glucuronidase in cold Reagent 7.3.4)

7.3.6    95% (v/v) Ethanol
(Prepare 20 ml in deionized water using 200 Proof USP Ethyl Alcohol, Sigma Product Number Z5130 .)

7.3.7    0.05% (w/v) Phenolphthalein Standard Solution (Std Soln)
(Prepare 2 ml by dissolving 1.0 mg of Phenolphthalein, Sigma-Aldrich Product Number P9750 in Reagent 7.3.6)

7.4 ASSAY:

7.4.1    Pipette (in milliliters) the following reagents into suitable containers:

  Test Blank
Reagent A (Buffer) 0.70 0.70
Reagent B (PheP-Gluc) 0.70 0.70


7.4.2    Mix by inversion and equilibrate to 37°C. Then add:

  Test Blank
Reagent E (Enzyme Solution) 0.10 -----


7.4.3    Mix by inversion and incubate at 37°C for exactly 30 minutes. Then add:

  Test Blank
Reagent C (Glycine Buffer) 5.00 5.00
Reagent E (Enzyme Solution) ----- 0.10


7.4.4    Immediately mix by inversion. Transfer the solutions to suitable cuvettes and record the A540nm for both the Test and Blank using a suitable spectrophotometer.


Prepare a standard curve by pipetting (in milliliters) the following reagents into suitable containers:

  Std 1 Std 2 Std 3 Std 4 Blank
Reagent A (Buffer) 0.70 0.70 0.70 0.70 0.70
Reagent B (PheP-Gluc) 0.70 0.70 0.70 0.70 0.70
Reagent G (Std Soln) 0.03 0.05 0.07 0.10 -----
Reagent F (Ethanol) 0.07 0.05 0.03 ----- 0.10
Reagent C (Glycine Buffer) 5.00 5.00 5.00 5.00 5.00


7.4.6    Mix by inversion and transfer the standards to suitable cuvettes. Record the A540nm for each standard using a suitable spectrophotometer.

8. Calculations

8.1    Standard Curve:

ΔA540 Standard = A540 Standard - A540 Standard blank
Prepare a standard curve by plotting the ΔA540 for the Standard vs micrograms of Phenolphthalein.

8.2    Sample Determination:

ΔA540 Sample = A540 Sample - A540 Sample blank
Determine the total micrograms of phenolphthalein liberated using the Standard curve.

Units/ml enzyme = (mg phenolphthalein released)(2)(df)


2 = Conversion factor from 30 minutes to 1 hour as per the Unit Definition
df = Dilution factor
0.1 = Volume (in milliliter) of enzyme used

Units/mg solid =   Units/mL enzyme  
mg solid/mL enzyme


Units/mg protein = Units/mL enzyme
mg protein/mL enzyme

9. Final Assay Contentration

In a 1.50 ml reaction mix, the final concentrations are 47 mM Sodium Acetate, 0.56 mM Phenolphthalein Glucuronic Acid, and 25-50 units b-Glucuronidase.

10. References & Attachments

10.1    Fishman, W.H. and Bernfeld, P. (1955) Methods in Enzymology, Volume I, 262-269

10.2    Combie, J., Blake, J.W., Nugent, T.E., and Tobin, T. (1982) Clin. Chem 28, 83-86

10.3    Fishman, W.H. (1974) in Methods of Enzymatic Analysis (Bergmeyer, H.U. ed) 2nd ed., Volume II, 929-932, Academic Press, New York, NY

11. Notes

11.1    This assay is not to be used to assay b-Glucuronidase, Insoluble Enzyme attached to beaded Agarose, Sigma Product Number G4506 .

11.2    This assay is based on the cited references.

11.3    History indicates product is fairly stable.

11.4    Use P9750 as Phenolphthalein Standard, or Standard Solution 105-1 while supplies last.

11.5    Sigma warrants that the above procedure information is currently utilized at Sigma and that Sigma products conform to the information in Sigma publications. Purchaser must determine the suitability of the information and products for its particular use. Upon purchase of Sigma products, see reverse side of invoice or packing slip for additional terms and conditions of sale.

12. Approval

  Print Name Sign Name Title Date
Prepared by: Carrie Cupp Carrie Cupp Chemist 7/20/04
Approved by: David Lintz David Lintz Supervisor, Analytical Services 8/13/04
Approved by: Gene McNaughton Gene McNaughton Quality Assurance 8/16/04


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