Enzymic Formation of β-Alkyl Glycosides by β-Galactosidase from Aspergillus oryzae and Its Application to the Synthesis of Chemically Unstable Cardiac Glycosides

β-Galactosidase obtained from Aspergillus oryzae was found to have strong transglycosylation activity. The glycosylation of water-soluble and insoluble alcohols was successfully performed under mild conditions (pH 5 at 4-37°C) with this enzyme. The enzyme was also applied to the onestep synthesis of several cardiac glycosides that are diffcult to obtain by ordinary chemical methods.