Kinetics and stability of delta 5-3-ketosteroid isomerase from Pseudomonas testosteroni in the system of reverse micelles of aerosol OT in isooctane.

Partially purified delta 5-3-ketosteroid isomerase (KSI) from Pseudomonas testosteroni was studied kinetically after solubilization in reverse micelles of aerosol OT (AOT) in isooctane and water, as regards its application to biotechnology. With delta 5,10-estren-17 beta-ol-3-one as a substrate, KSI displays an enzyme activity in the micellar system but a low stability. In the presence of urea, the enzyme is, however, stable. Kinetic parameters of the stabilized enzyme are highly sensitive to both the hydration degree of the surfactant and its concentration. The hypothesis of the geometric correspondence of a non-spherical enzyme and spherical micellar matrix is considered.