Enzymatic transformation of desacetyl-lanatoside A into digitoxin by β-glucosidase action in cyclodextrin solutions

Abstract

The enzymatic transformation of desacetyl-lanatoside A (DLA) to its secondary glycoside, digitoxin, in solutions of β-and γ-cyclodextrins is effected using of β-glucosidase from barley. Due to the interaction of cyclodextrins (CyDs) with desacetyl-lanatoside A, an increase in solubility of the latter of 24.5 and 230 times was observed for β-cyclodextrin and γ-cyclodextrin, respectively. Kinetic studies of the enzymatic transformation gave for β-glucosidase the values KM=3.3×10-4 mol. dm-3 and Vmax=0.557 μmol mg-1 min-1 when the substrate was the deacetyl-lanatoside A complex with β-cyclodextrin, while in the case of the complex with γ-cyclodextrin these values were KM=5.45×10-4 mol dm-3 and Vmax=0.896 μmol mg-1 min-1. © 1991 Science and Technology Letters.