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NAD + ‐Dependent Enzymatic Route for the Epimerization of Hydroxysteroids
Author(s) -
Tonin Fabio,
Otten Linda G.,
Arends Isabel W. C. E.
Publication year - 2019
Publication title -
chemsuschem
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 2.412
H-Index - 157
eISSN - 1864-564X
pISSN - 1864-5631
DOI - 10.1002/cssc.201801862
Subject(s) - nad+ kinase , chemistry , epimer , hydroxysteroid dehydrogenases , ursodeoxycholic acid , biocatalysis , cholic acid , enzyme , oxidoreductase , chenodeoxycholic acid , biochemistry , stereochemistry , bile acid , catalysis , dehydrogenase , reaction mechanism
Epimerization of cholic and chenodeoxycholic acid (CA and CDCA, respectively) is a notable conversion for the production of ursodeoxycholic acid (UDCA). Two enantiocomplementary hydroxysteroid dehydrogenases (7α‐ and 7β‐HSDHs) can carry out this transformation fully selectively by specific oxidation of the 7α‐OH group of the substrate and subsequent reduction of the keto intermediate to the final product (7β‐OH). With a view to developing robust and active biocatalysts, novel NADH‐active 7β‐HSDH species are necessary to enable a solely NAD + ‐dependent redox‐neutral cascade for UDCA production. A wild‐type NADH‐dependent 7β‐HSDH from Lactobacillus spicheri ( Ls 7β‐HSDH) was identified, recombinantly expressed, purified, and biochemically characterized. Using this novel NAD + ‐dependent 7β‐HSDH enzyme in combination with 7α‐HSDH from Stenotrophomonas maltophilia permitted the biotransformations of CA and CDCA in the presence of catalytic amounts of NAD + , resulting in high yields (>90 %) of UCA and UDCA.