Enzymatic synthesis of alkyl-α-glucoside catalysed by a thermostable α-transglucosidase in solvent-free organic medium

alpha-Transglucosidase from Talaromyces duponti was used to synthesize different alkyl-alpha-D-glucosides from alpha(1-4) linked carbohydrate donors. The enzymatic preparation, purified by a single step, consisting of hydrophobic interaction chromatography, was sufficiently pure for very stereospecific synthesis to be achieved. Biphasic and homogeneous organic media could be compared for such purposes. Yields appeared to be two- to threefold higher in low-water biphasic media. High concentrations of the glucosyl donor were present in the aqueous phase, while water-immiscible alcohols were used as glucosyl accepters. The high efficiency of the method was attributed to the shift of the thermodynamic equilibrium thanks to the extraction of the product from the aqueous phase, where the reaction occurs, into the organic phase. Operated in a continuous biphasic reactor, T. duponti alpha-transglucosidase showed a good thermostability with a half-life of 23 days at 30 degrees C.