glucuronidases

Glucuronidases are enzymes that hydrolyze glucuronides, releasing glucuronic acid from a wide range of substrates. They include the human lysosomal beta-glucuronidase (EC 3.2.1.31) and a broad family of microbial enzymes produced by bacteria, fungi, and archaea.

Human beta-glucuronidase is encoded by the GUSB gene and is localized to lysosomes where it functions at acidic pH to cleave glucuronic acid from conjugates such as bilirubin diglucuronide, steroid and drug glucuronides, and glycosaminoglycan fragments. Deficiency of this enzyme causes mucopolysaccharidosis type VII (Sly syndrome).

Microbial glucuronidases reside in the gut and other environments. In the intestinal lumen they deconjugate glucuronides produced by the host or by drugs, enabling reabsorption of aglycones and potentially influencing drug pharmacokinetics, toxin reactivation, and gut health. Bacterial glucuronidases are considered therapeutic targets to mitigate side effects of chemotherapy (for example irinotecan) and to modulate enterohepatic recycling of xenobiotics.

Measurement and study of glucuronidases employ substrates such as p-nitrophenyl-beta-D-glucuronide and natural substrates; assays and inhibitors are used in research and drug development.