Morphine glucuronide hydrolysis: Superiority of β-glucuronidase from Patella vulgata

β-Glucuronidase from Patella vulgata, Helix aspersa, Helix pomatia, and bovine liver were evaluated for usefulness in routine hydrolysis of drug-glucuronic acid conjugates from equine urine samples. Factors affecting the reaction rate (enzyme concentration, ligand concentration, temperature, and pH) were optimized. A 3-h incubation at 65 ° C with 5000 U of β-glucuronidase from P. vulgata per millimeter of urine resulted in complete hydrolysis of all morphine glucuronide in the urine samples. Not only was the enzyme preparation from P. vulgata the most cost-effective β-glucuronidase source studied, but also its thermal stability is such that it can be used at a temperature high enough to substantially shorten the incubation interval. Preliminary work on other drugs that form glucuronide conjugates indicates that this same procedure is similarly superior for use in their hydrolysis.