The bioconversion of 17α-ethynyl steroids with 11α-hydroxylase ofRhizopus nigricans

Abstract

The bioconversion of 17α‐ethynyl steroids was effected with 11α‐hydroxylase of Rhizopus nigricans. 7β‐Hydroxyethisterone was found after the bioconversion of ethisterone, and 10β‐ and 6β‐hydroxy derivatives after the bioconversion of norethisterone. It seems that the ethynyl group prevents steroid‐enzyme binding in the normal mode and thus inhibits the formation of an 11α‐hydroxylated product.