Characterization of rabbit morphine 6-dehydrogenase and two NAD+-dependent 3α(17β)-hydroxysteroid dehydrogenases

► Novel rabbit aldo-keto reductases (AKRs: 1C26, 1C27 and 1C28) were cloned. ► AKR1C26 was identified with morphine 6-dehydrogenase reported previously. ► The three enzymes showed NAD+-dependent 3α/17β-hydroxysteroid dehydrogenase activity. ► AKR1C27 differed from AKR1C28 in kinetic properties, despite their high identity. ► The two residues (Tyr118 and Phe310) play critical roles in their ligand binding.