Purification of glucosyltransferase from cell-lysate of Streptococcus mutans by counter-current chromatography using aqueous polymer two-phase system

Abstract

Counter-current chromatography (CCC) using a cross-axis coil planet centrifuge (X-axis CPC) was applied to the purification of glucosyltransferase (GTF) from a cell-lysate of cariogenic bacteria. The purification was performed using an aqueous polymer two-phase system composed of 4.4% (w/w) polyethylene glycol (PEG) 8000–6% (w/w) dextran T500 containing 10 mM phosphate buffer at pH 9.2 by eluting the upper phase (UP) at 1.0 ml/min. The bacterial GTF in the cell-lysate of Streptococcus mutans was selectively retained in the dextran-rich lower stationary phase. The column contents were diluted and subjected to hydroxyapatite (HA) chromatography to remove the polymers from the GTF. Fractions eluted with 500 mM potassium phosphate buffer were analyzed by GTF enzymatic activity as well as sodium dodecyl sulfate polyacrylamide gel electrophoresis (SDS–PAGE). The GTF purity in the final product was increased about 87 times as that in the cell-lysate with a good recovery rate of about 79% through this purification process.