Analysis of mandelonitrile lyase and beta-glucosidase from sweet almonds by combined electrophoretic techniques.

Almonds are a rich source of mandelonitrile lyase (oxynitrilase) and beta-glucosidase. The isolation of these two enzymes from sweet almonds requires fractional ammonium sulfate precipitation followed by ion-exchange chromatography on diethylaminoethyl-(DEAE) and carboxymethylcellulose (CMC) columns. In the present investigation different electrophoretic techniques such as sodium dodecyl sulfate-polyacrylamide gel electrophoresis (SDS-PAGE), isoelectric focusing in immobilized pH gradients (IEF-IPG), and capillary electrophoresis were used to characterize these two enzymes. For the first time, beta-glucosidase and oxynitrilase were separated in an immobilized pH gradient of one pH unit. Capillary zone electrophoresis (CZE) was an excellent tool for analysis of the purity of enzyme preparations, achieving complete separation of various protein constituents in only 15 min. CZE showed a resolving capacity for the separation of enzyme forms comparable to that of isoelectric focusing in an immobilized pH gradient.