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protein structure communications
Mouse 3(17)α-hydroxysteroid dehydrogenase (AKR1C21) is a bifunctional enzyme that catalyses the oxidoreduction of the 3- and 17-hydroxy/keto groups of steroid substrates such as oestrogens, androgens and neurosteroids. The structure of the AKR1C21–NADPH binary complex was determined from an orthorhombic crystal belonging to space group P212121 at a resolution of 1.8 Å. In order to identify the factors responsible for the bifunctionality of AKR1C21, three steroid substrates including a 17-keto steroid, a 3-keto steroid and a 3α-hydroxysteroid were docked into the substrate-binding cavity. Models of the enzyme–coenzyme–substrate complexes suggest that Lys31, Gly225 and Gly226 are important for ligand recognition and orientation in the active site.
Keywords: 3(17)α-hydroxysteroid dehydrogenase.