In enzymology, a corticosteroid side-chain-isomerase () is an enzyme that catalyzes the chemical reaction
Hence, this enzyme has one substrate, 11-deoxycorticosterone, and one product, 20-hydroxy-3-oxopregn-4-en-21-al.
This enzyme belongs to the family of isomerases, specifically those intramolecular oxidoreductases interconverting aldoses and ketoses. The systematic name of this enzyme class is 11-deoxycorticosterone aldose-ketose-isomerase.