Enzyme catalyzed synthesis of alkyl-glucosides, alkyl-polyglucosides and aryl-oligosaccharides using whole cell of pichia etchellsii (β-glucosidase) in micro aqueous and organic media

Abstract

Glycoconjugates are key biomolecules in essentially all living organisms with multiple functions including energy storage, cell recognition, immune responses and thus have considerable potential as therapeutic agents, besides that they are employed in manifold applications as bio surfactants. Alkyl-glucosides and alkyl-polyglucosides are wellcharacterized eco-friendly surfactants and have wide range of applications in personal care, biomembrane investigation and within the pharmaceutical area.These consist of a hydrophilic head group which can be any sugarand a hydrophobic tail, which can be either a fatty acid residue or an alcohol.Aryl-oligosaccharides are suitable substrates for characterizing novel enzymes and are widely used in transglycosylation reactions as glycosyl acceptors for enzymatic synthesis of different di- and trisaccharides. Tri- and tetra saccharides are of special interest,particularly those with a _-1,3/1,6 glycosidic linkage pattern as these show strong immuno-modulatory activity as biological response modifiers. The development of an efficient enzymatic methodology for their synthesis is in high demand. Glycosidases have been extensively studied as biocatalysts for these bioconversions. Currently, the industrial production of these molecules is carried out by two chemical methods, namely, Fischer glycosylation and Koenigs-Knorr reaction. These routes involve extremes of temperature, pressure, use of toxic catalysts, and multiple protection/deprotection/activation steps. It is obvious that there is a lot to be gained in terms of atom economy, reduced waste generation, use of safer solvents, reduced energy consumption, etc., if chemical routes are replaced by enzymatic synthesis. Two methods, namely, reverse hydrolysis and transglycosylation, have been used for the synthesis of thesecompounds. Several _-glucosidases have been investigated for this purpose.