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

Summary

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 K_M=3.3×10⁻⁴ mol. dm⁻³ and V_max=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 K_M=5.45×10⁻⁴ mol dm⁻³ and V_max=0.896 μmol mg⁻¹ min⁻¹.