title: Purification and biochemical characterization of a specific beta-glucosidase from the digestive fluid of larvae of the palm weevil, Rhynchophorus palmarum.
abstract: A beta-glucosidase was purified from the digestive fluid of the palm weevil Rhynchophorus palmarum L. (Coleoptera: Curculionidae) by chromatography on anion-exchange, gel filtration, and hydrophobic interaction columns. The preparation was shown to be homogeneous on polyacrylamide gels, beta-glucosidase is a monomeric protein with a molecular weight of 58 kDa based on its mobility in SDS-PAGE and 60 kDa based on gel filtration. Maximal beta-glucosidase activity occurred at 55 degrees C and pH 5.0. The purified beta-glucosidase was stable at 37 degrees C and its pH stability was in the range of 5.0-6.0. The enzyme readily hydrolyzed p-nitrophenyl-beta-D-glucoside, cellobiose, cellodextrins and required strictly beta-gluco configuration for activity. It cleaved glucose-glucose beta-(1-4) linkages better than beta-(1-2), beta-(1-3) and beta-(1-6) linkages. The catalytic efficiency (K(cat)/K(M)) values for p-nitrophenyl-beta-D-glucoside and cellobiose were respectively 240.48 mM(-1)s(-1) and 134.80 mM(-1)s(-1). Beta-glucosidase was capable of catalysing transglucosylation reactions. The yield of glucosylation of 2-phenylethanol (20 %), catalysed by the beta-glucosidase in the presence of cellobiose as glucosyl donor, is lower than those reported previously with conventional sources of beta-glucosidases. In addition, the optimum pH is different for the hydrolysis (pH 5.0) and transglucosylation reactions (pH 6.6).
authors.affiliation: Laboratoire de Biochimie et Technologie des Aliments de l'Université d'Abobo-Adjamé Abidjan, Côte d'Ivoire, 02 BP 801 Abidjan 02, Côte d'Ivoire. yapissoi@yahoo.fr
authors.forename: Désiré
authors.initials: D
authors.lastname: Yapi Assoi Yapi
authors.forename: Dago
authors.initials: D
authors.lastname: Gnakri
authors.forename: Sebastien
authors.initials: S
authors.lastname: Lamine Niamke
authors.forename: Lucien
authors.initials: L
authors.lastname: Patrice Kouame
mesh_terms: D000818:Animals; D004795:Enzyme Stability; D041981:Gastrointestinal Tract / Q000201:enzymology; D006863:Hydrogen-Ion Concentration; D007814:Larva / Q000201:enzymology; D008970:Molecular Weight; D013379:Substrate Specificity; D013696:Temperature; D048889:Weevils / Q000201:enzymology*; D001617:beta-Glucosidase / Q000737:chemistry / Q000302:isolation & purification* / Q000378:metabolism
chemical_list: D001617:beta-Glucosidase