Comparison of enzymic activity and nanostructures in water/ethanol/Brij 35 and water/1-pentanol/Brij 35 systems

Abstract

The kinetics of enzyme-catalyzed alc. oxidn. has been measured in liq. water/ethanol/Brij 35 and water/1-pentanol/Brij 35 systems, essentially in the water-rich regions. For the ethanol systems it was found that the enzymic activity sharply decreases with increasing alc. concn. independently of the surfactant concn. between 0 and 22 mass %. In the case of the 1-pentanol systems the enzymic activity decreases also with increasing alc. concn., but this decrease can considerably be attenuated by adding increasing amts. of surfactant. To explain these results at the nanometer level, small-angle neutron-scattering (SANS) expts. have been carried out on these systems. The comparison of the scattering and the kinetic measurements suggests the following interpretation. In all cases, the enzymic activity depends on the concn. of the alc. in the aq. phase or in the aq. pseudophase contg. the enzyme. A certain amt. of alc. may be present in an org. pseudophase formed by direct micelles. In the case of the 1-pentanol systems the alc. participates in the structuration of the micelles and is concd. in the micelles, whereas in the case of the ethanol systems the alc. remains essentially in the aq. pseudophase and even destroys the micelles. These results suggest that in some cases enzymic activity can be used as a probe to detect some aspects of the mol. organization of a complex liq.