Almond-emulsin β-d-glucosidase and β-d-galactosidase

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Abstract
[beta]-D-Galactosidase and [beta]-D-glucosidase activities have been measured in sweet-almond emulsin with the p-nitrophenyl hexosides. The pH optima in hydrochloric acid-sodium butyrate buffers were between 5.5 and 5.6. No separation of the two activities was achieved by ammonium sulphate fractionation or by partial heat inactivation. D-Glucose, D-galactose, D-glucono-l-[forward arrow]4-lactone and D-galactono-l-[forward arrow]4-lactone were competitive inhibitors with similar Ki values when measured against the two substrates. Mixed substrate experiments supported the conclusion that one enzyme site is responsible for both activities.