Transglycosylation reactions by exoglycosidases from the termite Macrotermes subhyalinus

The ability of four exoglycosidases (beta -galactosidase, beta -glucosidase , alpha -glucosidase and invertase) from the termite Macrotermes subhyalinu s to catalyse tranglycosylation reactions was tested using lactose, cellobi ose, maltose and sucrose as glycosyl donors and 2-phenylethanol as glycosyl acceptor. The experimental conditions were optimized in relation to the ti me course of the reaction, pH and concentrations of glycosyl donor and acce ptor. Whereas the hydrolytic activity was largely predominant over the tran sferase activity with beta -galactosidase and beta -glucosidase, the transg lycosylation activity represented 68% with alpha -glucosidase. In addition, as demonstrated by the transglycosylation product formed, the hydrolysis o f sucrose was catalysed by alpha -glucosidase and not by invertase. On the basis of this work, alpha -glucosidase from M. subhyalinus appears to be a valuable tool for the preparation of neoglycoconjugates.