Mechanisms of steroid oxidation by microorganisms.

Two enzymes are responsible for the cleavage of pregnane side chains. A steroid-inducible oxygenase, in the presence of reduced nicotinamide adenine trinucleotide and molecular oxygen, catalyzes the conversion of progesterone into testosterone acetate. The latter ester is then hydrolyzed by an esterase to yield testosterone. The oxygenase has been partially purified and separated from the esterase. Evidence is herein presented to show that these two enzymes are also responsible for the degradation of pregnane side chains in 17a-hydroxypregn-4-ene-3,20-dione, deoxycorticosterone, pregna-4,16-diene-3,20-dione and 16a,17aoxidopregn-4-ene-3,20-dione. capable of converting androst-4-ene-3,17-dione into 17a-oxaandrost-4-ene-3,17-dione. From these results, the conversion of progesterone into 17a-oxa-androst-4-ene-3,17-dione by microorganisms may be ostensibly represented as follows.