Hydrolysis of Aryl β-D-Glucofuranoside by Almond Emulsin β-Glucosidase

Abstract

1. β-D-Glucofuranosides of 2-naphthol, phenol, guaiacol and m-cresol were hydrolyzed by almond emulsin, and the hydrolysis was inhibited by glucono-1, 4-lactone and glucono-1, 5-lactone. 2. The kinetics of the hydrolysis of aryl β-D-glucofuranoside by almond emulsin β-glucosidase was investigated. The pH optimum of the β-D-glucofuranoside is between 5.0 and 5.25 in phosphate-citrate buffer at 30°. The Michaelis-Menten constant is : 2-naphthyl β-D-glucofuranoside, 2.0×10^-3 M ; phenyl β-D-glucofuranoside, 6.2×10^-2 M ; guaiacol β-D-glucofuranoside, 5.5×10^-2 M ; m-cresyl β-D-glucofuranoside, 5.0×10^-2 M. The kinetics of the hydrolysis of the corresponding glucopyranoside by the enzyme was also investigated. The pH optimum is approximately the same as furanoside. The Michaelis-Menten constant is : 2-naphthyl β-D-glucopyranoside, 1.4×10^-3 M ; phenyl β-D-glucopyranoside, 4.0×10^-2 M ; guaiacol β-D-glucopyranoside, 3.2×10^-2 M ; m-cresyl β-D-glucopyranoside, 2.2×10^-2 M. 3. In view of the above facts, it was concluded that β-D-glucofuranoside could be a substrate for almond emulsin β-glucosidase.