[Human glycosidase in the AOT reversed micelle system: features of properties and kinetic regularities of catalysis].

Kinetic of hydrolysis, by lysosomal glycosidases, of their synthetic substrates were studied in systems of the Aerosol OT (AOT) reversed micelles in octane. Catalytic activity of all the tested enzymes, viz., GM1-galactosidase, beta-hexosaminidases A and B, neuraminidase, and galactocerebrosidase, in reversed micelles proved to be the same as or higher than in the water buffer. In the reversed micelles an effective inhibition of the enzymatic reactions by the resulting carbohydrates was however observed. The dependence of the enzymes' activity on the hydration degree was represented by curves with one or several maxima, corresponding to various oligomeric forms of the enzymes. Dependencies of effective Km on the hydration degree in reversed micelles are similar dependencies of the enzyme activities on the same parameter, which can be explained by corresponding changes of local substrate concentration near the enzyme active site. Dependencies of the enzymatic activity on the surfactant's concentration in the reversed micellar system were also studied. Catalytic activity of the soluble lysosomal glycosidases was found to be unaffected by the micelles concentration. Activity of the membrane lysosomal glycosidase, galactocerebrosidase, strongly increased when the surfactant's concentration decreased. Under optimal conditions the activity of galactocerebrosidase in reversed micelles was 10-fold as compared with its activity in the water buffer.