Bacterial GUSB hydrolyses BDG to BIL

Stable Identifier
Reaction [transition]
Homo sapiens
Related Species
Clostridium perfringens
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Bilirubin diglucuronide (BDG) is a substrate for microbial β-glucuronidase, which can cleave the glucuronosyl moieties and liberate bilirubin for reabsorption through the basolateral surfaces of the intestines where it can undergo further metabolism or pass directly back into the circulation. This process, known as enterohepatic circulation, can extend the half-life of bilirubin while adding to the total serum bilirubin load (Seyfried et al. 1976). Conjugated bilirubin is excreted in bile through the duodenum, where it can be unconjugated by enteric bacteria (Kim et al. 1995). Many bacterial β-glucuronidases can cleave the glucuronosyl moieties from conjugated bilirubins in the human gut. In vitro assays reveal the C. perfringens species produce beta-glucuronidase enzyme activity that is at least 30-fold higher than other bacterial species (Leung et al. 2001).

Urobilinogen (D-urobilinogen) is closely related to two other compounds: mesobilirubinogen (I-urobilinogen) and stercobilinogen (L-urobilinogen). Somewhat confusingly, all three compounds are frequently collectively referred to as "urobilinogens".

Literature References
PubMed ID Title Journal Year
8845801 Purification and characterization of beta-glucuronidase from Escherichia coli HGU-3, a human intestinal bacterium

Han, MJ, Jin, YH, Jung, EA, Kobashi, K, Kim, DH

Biol. Pharm. Bull. 1995
793184 [Bilirubin metabolism (author's transl)]

Seyfried, H, Leithner, C, Penner, E, Klicpera, M

Wien. Klin. Wochenschr. 1976
11522976 Expression of bacterial beta-glucuronidase in human bile: an in vitro study

Chan, RC, Cheng, AF, Leung, JW, Liu, YL, Inciardi, JF, Leung, PS

Gastrointest. Endosc. 2001
Catalyst Activity

hydrolase activity, hydrolyzing O-glycosyl compounds of GUSB [extracellular region]

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