Hydrolysis of Phenyl /3-Maltoside Catalyzed by Saccharifying a-Amylase from Bacillus subtilis1

1. The hydrolytic reaction of phenyl /J-maltoside catalyzed by saccharifying a-amylase [EC 3.2.1.1] of Bacillus subtilis was studied at 25°C and pH 5.4, by measuring the total reducing power and the amount of phenol liberated, and by thin layer chromatography. 2. The enzyme hydrolyzed phenyl /S-maltoside at the glucosidic linkage between the two glu-cose residues to form D-glucose and phenyl j9-D-glucoside. Besides these products, maltose, maltotriose, and phenyl ^-maltotrioside were also observed as reaction products. The identifi-cation of phenyl /3-maltotrioside is described in detail. The formation of these products was attributed to the transglycosylation reaction of the enzyme. The time course of reaction as followed by reducing power measurement showed an induc-tion period of several minutes. In 1967, Yoshida, Hiromi, and Ono found that at a high concentration of phenyl a-maltoside as a substrate, glycosyl transfer reaction occurred during the hydrolysis catalyzed by saccharifying «-amylase [EC 3.2.1.1] of Bacillus subtilis, and that the amylase hydrolyzed the substrate at two dif-ferent linkages; between the D-glucose and phenyl residues to form maltose and phenol, and between the two glucose residues to form D-glucose and phenyl a-D-glucoside (1). To explain the kinetic behavior of this enzyme, they considered that, in addition to the active site, an activator site to whic