CATALYTIC ACTIVITY OF UREASE IN NONAQUEOUS MEDIA

The kinetics of urease-catalyzed urea hydrolysis has been studied in m ixtures of water with organic solvents (DMF, DMSO, ethanol, isopropano l, or dioxane), in detergent-free microemulsions (hexane-isopropanol-w ater), and inverted micelles formed by anionic, cationic, or nonionic detergents (Aerosol(R)-OT, cetyltrimethylammonium bromide, and Triton X-100, respectively), including mixed inverted micelles (Aerosol(R)-OT plus Triton X-100). The kinetic parameters of the reaction (k(cat) an d K-m) and the parameter ratios were determined for all the systems of urease-catalyzed urea hydrolysis in nonaqueous media. The value of k( cat)/K-m obtained for the enzyme incorporated into the mixed micelles was maximal, suggesting that under the conditions mimicking the natura l environment of urease its operation is most effective. Practical rec ommendations on the choice of organism solvents which ensure optimal c onditions for urease-catalyzed urea hydrolysis are provided as well.