Bacterial bile salt hydrolases (BSHs) play a pivotal role in bile acid metabolism through their dual enzymatic capabilities. Primarily, these enzymes function as hydrolytic catalysts that cleave the amide bonds in glycine- or taurine-conjugated bile salts, a critical first step in bile acid modification within the intestinal environment. BSHs exhibit broad substrate specificity, efficiently deconjugating major bile salts including glycocholate (GCA), glycodeoxycholate (GDCA), glycochenodeoxycholate (GCDCA), taurocholate (TCA), taurodeoxycholate (TDCA), and taurochenodeoxycholate (TCDCA), though they demonstrate a marked preference for glycine-conjugated substrates over taurine-conjugated ones. This deconjugation reaction liberates free bile acids (such as cholic acid or chenodeoxycholic acid) and the respective amino acid residues (glycine or taurine). This functional versatility allows gut bacteria to dynamically influence bile acid composition, with potential implications for host metabolism, inflammation, and disease susceptibility.

Bile Salt Deconjugation References