Stability and activity of 20 beta-hydroxysteroid dehydrogenase in microemulsion of non-ionic detergents

We report here the formation of a microemulsion with non-ionic detergents and cyclohexane. The activity and stability of 20 beta-hydroxysteroid dehydrogenase solubilized in all water systems and in microemulsions of Nonidet P-40: Triton X-35/water/cyclohexane was investigated. In the microemulsion the activity depended on the molecular ratio of water to surfactant (Wo); maximal activity was obtained at Wo of 8.4. The stability in the microemulsion was higher at Wo = 11.75 i.e. the enzyme, retained about 50% of activity after eight days.