Purification and characterisation of two alpha-glucosidases from termite workers macrotermes bellicosus (termitidae: macrotermitinae)

Objectives: The objective was to purify and characterise beta-glucosidases from termite Macrotermes bellicosus workers for use in glycobiotechnology and elucidate the role played by these enzymes in the degradation of plant material. Methodology and results: Two beta-glucosidases were purified by a three-step procedure consisting of ion-exchange, size-exclusion and hydrophobic interaction chromatography techniques. Beta-Glc A and B had molecular weights estimated at 204 and 216 kDa, respectively, by SDS-PAGE; and 209 and 230 kDa, respectively, by gel filtration. Both enzymes exhibited the same temperature and pH optima for pnitrophenyl-beta-D-glucopyranoside hydrolysis and were stable at 37°C. The enzymes showed a high specificity for the beta-glucosyl residue and preferred glucose-beta-(1-4) linkages to beta-(1-3), beta-(12) and beta-(1-6) linkages. Both beta-glucosidases were inhibited by sulfhydryl-binding reagents. Conclusions and application of findings: The enzymes isolated in this study appear to be distinct from other known beta-glucosidases in terms of substrate specificity and low K M value for cellobiose. The physiological role of the two beta-glucosidases in the digestive tract of the termite could be the digestion of di-and oligosaccharides derived from celluloses. The enzymes could be used as a tool in the structural analysis of D-glucose containing oligosaccharide chains of glycoproteins , glycolipids and cellulose.