Substrate Specificity and Some Properties of Crystalline Mold Maltase

Abstract

The substrate specificity of crystalline mold maltase was investigated.
The enzyme acts upon various α-heteroglucosides or saccharides. Aryl-α-glucosides were hydrolyzed much faster than alkyl-α-glucosides. The enzyme acts on the maltose derivatives whose reducing groups have been masked. But among glucosylfructoses turanose, maltulose and isomaltulose were attacked with a slow rate while the enzyme was quite inert to sucrose. Malto-and isomalto-oligosaccharides were also hydrolyzed and the enzyme ceased its action at seven to eight units of hexose in both series of oligosaccharides.
The opt. pH range of Takamaltase was 4.2-4.6 and opt. temp., 50-55°C. Cu⁺⁺ and Hg⁺⁺ strongly inhibited the enzyme activity but other metal ions tested had no effects. It is suggested that the enzyme is not a sulfhydryl enzyme because of the lack of effects of SH-reagents on the activity.