3β-hydroxy-Δ5-steroid dehydrogenase

3β-hy·droxy-Δ⁵-ste·roid de·hy·dro·gen·ase (hi-drok″se-sterґoid de-hiґdro-jən-ās) [EC 1.1.1.145] an enzyme of the oxidoreductase class that catalyzes the dehydrogenation and isomerization of 3β-hydroxysteroids (e.g., pregnenolone) to 3-ketosteroids (e.g., progesterone), a step occurring in the biosynthetic pathways of all classes of corticosteroids.