Comparison between p-nitrophenyl glucuronide and phenolphthalein glucuronide as substrates in the assay of beta-glucuronidase.

The p -nitrophenyl glucuronide method for the determination of β-glucuronidase activity is compared with the phenolphthalein glucuronide method in a variety of diseases. It is shown that linear correlation exists between the two methods. The presence of isoenzymes, which would hydrolyze the substrates at different rates, is therefore excluded. The reaction conditions for the phenolphthalein glucuronide method are investigated and improved upon. Normal values for both methods in milliunits per milliliter are presented. The advantages of the p-nitrophenyl glucuronide method are indicated.