A novel polysaccharidase from major soldier of the termite Macrotermes subhyalinus was purified to homogeneity by a three-step procedure consisting of ion-exchange, size-exclusion and hydrophobic interaction chromatographies in order to elucidate its contribution to the degradation of plant material. The only substrates that were hydrolyzed by the purified enzyme were xylans and carboxymethylcellulose. The specific activities towards carboxymethylcellulose and xylan from Birchwood were respectively 2.00 and 2.75 U/mg of protein. The molecular weight was measured to be 78.90 kDa by gel filtration and 76.95 kDa by sodium dodecyl sulfate-polyacrylamide gel electrophoresis, indicating that the enzyme behaved as a monomer. The optimum temperatures of the enzyme were found to be 45°C using carboxymethylcellulose and 60°C using xylan from Birchwood as substrates which pointed out that this enzyme had separate sites for each activity. The pH-activity optimum was pH 5.0 for both substrates. The enzyme was capable of hydrolyzing both beta-1, 4-glucosidic and beta-1, 4-xylosidic bonds in cellulose and xylan respectively. Based on thin-layer chromatographic analysis of the degradation products, the cellulase activity produced cellobiose and cellodextrins from carboxymethylcellulose as the substrate. When xylan from Birchwood was used, end products were xylose, xylobiose and xylodextrins. The catalytic efficiency values for carboxymethylcellulose and xylan from Birchwood were respectively 13.60 and 31.74 U.ml/mg2. The polysaccharidase purified is an endo-beta-xylanase with endo-beta-glucanase activity. The enzyme catalyzed both hydrolysis and transglycosylation. It appears to be distinct from the other termite and Termitomyces sp cellulases and xylanases so far reported in terms of substrate specificity and low activity values against carboxymethylcellulose and xylans. The role of the purified enzyme in the digestive tract is the hydrolysis of amorphous cellulose and xylans from the plant material.

Keywords: Bifunctional enzyme; endo-beta-D-glucanase; endo-beta-D-xylanase; major soldier, physiological role; termite Macrotermes subhyalinus