Testicular and adrenal 3 beta-hydroxy-5-ene-steroid dehydrogenase and 5-ene-4-ene isomerase.

H Ishii-Ohba, H Inano, B Tamaoki

National Institute of Radiological Sciences, Chiba-shi, Japan.

Journal of steroid biochemistry 1987

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The purified multifunctional enzyme, 3 beta-hydroxysteroid dehydrogenase with steroid 5-ene-4-ene isom erase from rat testes and adrenals showed similar catalytic properties. They exhibited the same molecular weight of 46,500. Either NAD+ or NADH was required for steroid isomerizing activity, probably as an allosteric effector. It was clearly demonstrated by using the purified enzyme that without NAD(H) no isomerizing activity was detected. In the presence of NADH, or its analogue, 3 beta-hydroxysteroid dehydrogenase obtained from both tissues was inhibited; however, steroid isomerizing activity remained due to the allosteric effect. The results suggest that in these endocrine organs, both enzyme activities reside within the same protein.

Citation

H Ishii-Ohba, H Inano, B Tamaoki. Testicular and adrenal 3 beta-hydroxy-5-ene-steroid dehydrogenase and 5-ene-4-ene isomerase. Journal of steroid biochemistry. 1987;27(4-6):775-9