Use of Ionic Liquids to Increase the Yield and Enzyme Stability in the β-Galactosidase Catalysed Synthesis of N -Acetyllactosamine

The use of ionic liquids as alternative solvents for enzyme catalysis was investigated. β-Galactosidase from Bacillus circulans catalyses the synthesis of N -acetyllactosamine starting from lactose and N -acetylglucosamine in a transglycoslyation reaction. The addition of 25% v/v of 1,3-di-methyl-imidazol-methyl sulfate [MMIM] [MeSO 4 ] as a water-miscible ionic liquid suppresses the secondary hydrolysis of the formed product, resulting in doubling the yield to almost 60%. The enzyme can be reused several times after ultrafiltration of the reaction mixture without loss of activity. Results of different amounts of ionic liquids in the reaction medium on the thermostability of the galactosidase as well as on oxidoreductases are presented as well.