Interconversion of androst-4-ene-3,17-dione and testosterone by an enzyme from a Mycobacterium sp. or its resting cells
2001
Lo, C.K. | Wu, K.L. | Liu, W.H.
The interconversion of androst-4-ene-3,17-dione (AD) and testosterone (TS) using the enzyme 17 beta-hydroxysteroid dehydrogenase (17 beta-HSD) from a Mycobacterium sp. or the resting cells of the same organism was investigated. Cholesterol and AD were used as inducers for the production of 17 beta-HSD in cultures of Mycobacterium sp. 17 beta-HSD was purified from the cell-free extract by ammonium sulfate fractionation, Sepharose CL-6B and DE-52 column chromatographies. The purified enzyme was confirmed to be homogeneous by SDS-polyacrylamide gel electrophoresis, and the molecular weight was estimated to be 32,000. The optimal pH and temperature for the reversible interconversion of AD and TS in the presence of NADH and NAD+ were 6.0, 8.9 and 50 degrees C, respectively. The oxidation of TS to AD by the purified enzyme and resting cells were preferred to the reverse reduction reaction. The most important parameters for reduction of AD to TS using Mycobacterium cells was the induction of 17 beta-HSD in culture and the supply of reducing power, NADH, to the reaction system.
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