Purification and characterisation of strictosidine β-d-glucosidase from Catharanthus roseus cell suspension cultures

Strictosidine β-d-glucosidase (EC 3.2.1.105) was purified to apparent homogeneity from suspension cultured cells of Catharanthus roseus (L.) G. Don (Apocynaceae). It occurs in cell extracts as a high molecular mass protein complex. Native PAGE analysis showed the occurrence of three different forms. Digestion of the protein by trypsin resulted in disintegration of the complex, solubilising the enzyme without loss of activity. In cell extracts, the native enzyme forms probably consist of several subunits of 63 kDa. Determination of kinetic parameters showed that it has a strong affinity for the substrate (strictosidine, Km ≤ 20 μM).