Ecdysone 20-monooxygenase () is an enzyme that catalyzes the chemical reaction
The three substrates of this enzyme are ecdysone, a reduced electron acceptor, and oxygen. Its products are the insect molting hormone, 20-hydroxyecdysone, the oxidised acceptor, and water.
This enzyme contains cytochrome P450 acting as an oxidoreductase. The systematic name of this enzyme class is . The genes in the ecdysone synthesis pathway are called halloween genes: this has the nickname shade; other names in common use include alpha-ecdysone C-20 hydroxylase, and ecdysone 20-hydroxylase.
References