Submitted to: Book Chapter
Publication Type: Book / Chapter
Publication Acceptance Date: May 1, 2006
Publication Date: December 26, 2006
Citation: Price, N.P. 2006. Ionic liquids: the prospects of enzyme-catalyzed glycosylations without water. In: Hou, C.T., Shaw, J-F., editors. Biocatalysis and biotechnology for functional foods and industrial products. 1st edition. New York, NY: CRC Press, Taylors and Francis Group. p. 451-466. Technical Abstract: Reversing the hydrolytic reaction catalyzed by glycosidases has great potential for the enzyme-catalyzed synthesis of new glycoconjugates. Hydrolysis of glycosidic bonds requires water as a co-reactant, and the reverse reaction (referred to as transglycosylation) is therefore favored by low- or non-aqueous conditions. The aim, therefore, is to lower the relative concentration of water, thereby shifting the equilibrium away from hydrolysis. This has been approached by using artificially high substrate concentrations, organic solvents, high salt buffers, or genetically-modified glycosidases. In addition, for nucleophilic hydrolysis via an SN2 mechanism the reaction rate is enhanced in a protic solvent such as water. Therefore, for glycosylations a second aim is to increase the ionic concentration of the solvent so as to favor nucleophilic substitution. This chapter will focus on the prospects of using ionic liquids as non-reactive solvents for glycosidase catalyzed transglycosylation reactions.