EXAMPLE 2 18-homo- 17 6-3 henylpropionyloxyestra-4,9-dien-3-one Add 3-phenylpropic-nyl chloride (12 cc.) in benzene (50 cc.) to (i)-18-hoino-17 3-liydroxyestr-5(10)=en-3 one (11 g.) in pyridine (50 cc.) at 18. Leave the mixture overnight at; 10 and add to crushed ice and acidify with 20% hydrochloric acid. Collect the product with benzene-ether and evaporate the solvent to give a residue which is recrystallised from benzene-ether to give 13- homo-17B-3'-phenylpropionyloxyestra 4,9-dien-3-0ne (9 g.) . 127-129 light absorption 305 (21,600); infrared absorption (CHCl 1725, 1650, 1605 (Found: C, ; H, . C H O requires C, ; H, %).
AB - The Δ5-3-ketosteroid isomerase of Pseudomonas testosteroni promotes the conversion of Δ5-3-ketosteroids to the α,β-conjugated 3-ketosteroids by an unusual intramolecular rearrangement involving a cis, cis diaxial proton transfer from the 4β- to the 6β-position. The enzyme is available as a pure protein in two crystalline forms of known unit cell dimensions and crystallographic symmetry (monoclinic and hexagonal). The amino acid sequence of the protomer has been established. Many lines of evidence suggest a mechanism of isomerization involving an enolic intermediate and the participation of an acidic and a basic group of the enzyme in the catalytic process. Single histidyl and aspartyl residues may be involved in the isomerization process and a mechanism for their participation is proposed. Certain β,γ-acetylenic 5,10-seco-3-ketosteroids are converted by the isomerase to the corresponding α,β-unsaturated allene(s) which irreversibly inactivate the enzyme. A partial purification of the soluble isomerase of rat liver has been achieved. These preparations are profoundly and specifically activated by reduced glutathione. The precise mechanism of this effect remains to be established.
Cell extracts prepared anaerobically from Clostridium innocuum and Clostridium paraputrificum reduced delta 4-3-ketosteroids to 3 beta 5 beta and 3 alpha 5 beta derivatives, respectively. delta 4-3-Ketosteroid-5 beta-reductase (5 beta-reductase) from both organisms required NADH for activity. 5 beta-Reductase from C. innocuum had a pH optimum of . The substrate concentration at half-maximal reaction velocity was microM, and a specific activity of 17 nmol product formed/h per mg protein was determined using 4-pregnen-3,20-dione (progesterone) as a substrate. delta 4-3-Ketosteroid-5 beta-reductase from C. innocuum reduced progesterone and testosterone, but not 4-cholesten-3-one, to corresponding 3-keto-5 beta derivatives. A relative molecular (Mr) weight of 80 000 was estimated for 5 beta-reductase using HPLC-gel filtration chromatography. 3 beta-Hydroxysteroid dehydrogenase in cell extracts of C. innocuum was oxygen sensitive and required NADH for activity. An Mr of 80 000 was estimated for 3 beta-hydroxysteroid dehydrogenase. However, 5 beta-reductase and 3 beta-hydroxysteroid dehydrogenase activities were separated using an HPLC-DEAE chromatography technique.