Kinetic properties of β-glucosidase from cassava

Abstract

β-Glucosidases from the leaf, peel and tuber cortex of cassava cv. Merah Jambu exhibited linamarase activity and had in common many kinetic properties. They were also capable of hydrolysing p-nitrophenyl-β-d-monoglycosides and cyanogenic β-monoglucosides but lacked activity towards the p-nitrophenyl-β-d-diglycosides, a cyanogenic diglucoside, and other β- or α-linked disaccharides. The Km values for p-nitrophenyl-β-d-monoglycosides were generally lower than those for linamarin, prunasin and salicin. Ag2+ inhibited both β-glucosidase and linamarase activities. Glucono-1,5-lactone inhibited the enzyme competitively, irrespective of the substrates used, while imidazole showed competitive inhibition with linamarin but non-competitive (mixed) inhibition with p-nitrophenyl-β-d-glucoside. The enzyme was unaffected by glucose. © 1989.