3-Hydroxy-9,10-secoandrosta-1,3,5(10)-triene-9,17-dione monooxygenase

3-hydroxy-9,10-secoandrosta-1,3,5(10)-triene-9,17-dione monooxygenase (, HsaA) is an enzyme with systematic name . This enzyme catalyses the following chemical reaction:


 * 3-hydroxy-9,10-secoandrosta-1,3,5(10)-triene-9,17-dione + FMNH2 + O2 $$\rightleftharpoons$$ 3,4-dihydroxy-9,10-secoandrosta-1,3,5(10)-triene-9,17-dione + FMN + H2O

This bacterial enzyme participates in the degradation of several steroids, including cholesterol and testosterone.