Abstract
p-Nitrophenyl β-xyloside is specifically hydrolysed by β-xylosidase. For this enzyme there are two different, namely Taka and emulsin, types. They are differentiated by the mode of substrate-enzyme complex formation. The enzyme of Taka type unites at first with xylose residue of β-xyloside; while in the case of emulsin type the first union with the substrate takes place at the β-heteroside linkage. The hydrolysis by the Taka β-xylosidase is inhibited by xylose, phenyl β-xyloside and xylonolactone, but not at all by other sugars and their corresponding derivatives, while the activity of emulsin β-xylosidase is inhibited by phenyl β-xyloside as well as by phenyl β-glucoside. Xylonolactone inhibits not only β-xylosidase of emulsin type also β-glucosidase and β-galactosidase of the same type. However, monolactones of saccharic acids lack an inhibitory effect upon all β-heterosidases of both types.
This investigation was supported by the Grant for Scientific Research of the Ministry of Education.
