Application of a simple diffusion model for the enzymatic activity of α-chymotrypsin in reverse micelles

Abstract

In reverse micellar systems, solubilized enzymes often display their highest activity at a particular w 0 value ( w 0 = [H 2 O] [surfactant]) ; below as well as above this value, the enzyme activity is lower. Recently, we have presented a theoretical model which describes this characteristic behavior in the case of hydrolytic enzymes, mainly on the basis of the diffusion theory [ M. Bianucci, M. Maestro, and P. Walde, Chem. Phys. 141, 273 (1990) ]. In this note, we report on some improvements of the model and we compare the theoretically calculated activity behavior with experimental data obtained for α-chymotrypsin in reverse micelles formed by the surfactant bis(2-ethylhexyl) sodium sulfosuccinate in isooctane. Although our theoretical calculations are not superimposable with the experimental values, the comparison indicates that inter- and/or intramicellar diffusion processes may affect the catalytic behavior of enzymes in reverse micellar systems.