Reaction: An unknown reductase reduces D-UBGN to STBN
- in pathway: Heme degradation
The D-urobilinogen (D-UBGN) that remains in the intestine is directly reduced to stercobilin (STBN) by unknown bacterial reductases. Stercobilins oxidize to form brownish pigments which lead to the characteristic brown colour found in normal feces (Vitek et al. 2006). STBN can also be reduced to stercobilinogen (L-urobilinogen), which can then be further oxidized to STBN. This constitutes the "enterohepatic urobilinogen cycle."
Reaction - small molecule participants:
STBN [extracellular region]
an oxidized electron acceptor [extracellular region]
D-UBGN [extracellular region]
a reduced electron acceptor [extracellular region]
Reactome.org reaction link: R-HSA-9661726
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Reaction input - small molecules:
D-Urobilinogen
electron acceptor
Reaction output - small molecules:
stercobilin
electron acceptor
Reactome.org link: R-HSA-9661726