Studies on almond emulsin beta-D-glucosidase. I. Isolation and characterization of a bifunctional isozyme

A beta-D-glucosidase (beta-D-glucoside glucohydrolase, EC 3.2.1.21) isozyme has been isolated from almond emulsin. The isolated enzyme is a glycoprotein and migrates as a single band on Sephadex G-200 filtration, CM 52 ion exchange chromatography, polyacrylamide gel electrophoresis, sodium dodecyl sulfate polyacrylamide gel electrophoresis and isoelectric focussing. The glucosidase and galactosidase activities traverse together during Sephadex G-200 gel filtration. Polyacrylamide gels stained specifically for the 2 enzymes reveal that the two activities comigrate. The molecular weight of the isozyme has been found to be 135 180 +/- 770, and that of its protomers to be 65 150 +/- 650.