Steroid Delta-isomerase

In enzymology, a steroid Delta-isomerase is an enzyme that catalyzes the chemical reaction


 * a 3-oxo-Delta5-steroid $$\rightleftharpoons$$ a 3-oxo-Delta4-steroid

Hence, this enzyme has one substrate, 3-oxo-Delta5-steroid, and one product, 3-oxo-Delta4-steroid.

This enzyme belongs to the family of isomerases, specifically those intramolecular oxidoreductases transposing C=C bonds. The systematic name of this enzyme class is 3-oxosteroid Delta5-Delta4-isomerase. Other names in common use include hydroxysteroid isomerase, steroid isomerase, Delta5-ketosteroid isomerase, Delta5(or Delta4)-3-keto steroid isomerase, Delta5-steroid isomerase, 3-oxosteroid isomerase, Delta5-3-keto steroid isomerase, and Delta5-3-oxosteroid isomerase. This enzyme participates in c21-steroid hormone metabolism and androgen and estrogen metabolism.

Structural studies
As of late 2007, 25 structures have been solved for this class of enzymes, with PDB accession codes, , , , , , , , , , , , , , , , , , , , , , , , and.