Synthesis and characterisation of galactosyl glycerol by β-galactosidase catalysed reverse hydrolysis of galactose and glycerol

A study of an enzymatic method for the production of galactosylglycerol is described. The effects of enzyme sources, enzyme amount, reaction temperature, reaction time, substrate ratio of glycerol to galactose, buffer content and pH on galactosylglycerol yield (mg/ml) were investigated. Under the optimum reaction conditions of β-galactosidases from Kluyveromyces lactis 240 U/ml, temperature 40 °C, time 24 h, buffer amount 60% (percent volume of buffer to that of substrates, pH 6.5), and the substrate molar ratio of 10 (glycerol16 mmol:galactose 1.6 mmol), the yield of galactosylglycerol was up to 116.47 mg/ml (galactose conversion 55.88%). The product was purified by activated charcoal and Sephadex G-15 column chromatography, up to 96%. The purified galactosylglycerol was fully characterised by MS and NMR, and identified as a mixture of (2R)- and (2S)- 3-O-β-D-galactopyranosyl-glycerol.