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Insights into the Substrate Promiscuity of Novel Hydroxysteroid Dehydrogenases
Author(s) -
Bertuletti Susanna,
Ferrandi Erica Elisa,
Marzorati Stefano,
Vai Marta,
Riva Sergio,
Monti Daniela
Publication year - 2020
Publication title -
advanced synthesis and catalysis
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.541
H-Index - 155
eISSN - 1615-4169
pISSN - 1615-4150
DOI - 10.1002/adsc.202000120
Subject(s) - chemistry , stereoselectivity , enzyme , cofactor , hydroxysteroid dehydrogenases , substrate (aquarium) , biocatalysis , stereochemistry , nad+ kinase , steroid , selectivity , enantiomer , aldo keto reductase , biochemistry , dehydrogenase , combinatorial chemistry , catalysis , reductase , biology , reaction mechanism , hormone , ecology
Hydroxysteroid dehydrogenases (HSDHs) are valuable biocatalysts for the regio‐ and stereoselective modification of steroids, bile acids and other steroid derivatives. In this work, we investigated the substrate promiscuity of this highly selective class of enzymes. In order to reach this goal, a preliminary search of HSDH homologues in in‐house or public available (meta)genomes was carried out. Eight novel NAD(H)‐dependent HSDHs, showing either 7α‐, 7β‐, or 12α‐HSDH activity, and including, for the first time, enzymes from extremophilic microorganisms, were identified, recombinantly produced, and characterized. Among the novel HSDHs, four highly active (up to 92 U mg −1 ) NAD(H)‐dependent 7β‐HSDHs showing negligible similarity towards previously described 7β‐HSDHs, were discovered. These enzymes, along with previously characterized HSDHs, were tested as biocatalysts for the stereoselective reduction of a panel of substrates including two α‐ketoesters of pharmaceutical interest and selected ketones that partially resemble the structural features of steroids. All the reactions were coupled with a suitable cofactor regeneration system. Regarding the α‐ketoesters, nearly all of the tested HSDHs showed a good activity toward the selected substrates, yielding the reduced α‐hydroxyester with up to 99% conversions and enantiomeric excesses. On the other hand, only the 7β‐HSDHs from Collinsella aerofaciens and Clostridium absonum showed appreciable activity toward more complex ketones, i. e., (±)‐trans‐1‐decalone, but with interesting as well as different selectivity.