Purification and biochemical characterization of an extracellular fructosyltransferase enzyme from sp. XOBP48: implication in fructooligosaccharide production.

An extracellular fructosyltransferase (Ftase) enzyme with a molar mass of ≈70 kDa from a newly isolated indigenous coprophilous fungus sp. XOBP48 is purified to homogeneity and characterized in this study. The enzyme was purified to 4.66-fold with a total yield of 15.53% and specific activity of 1219.17 U mg of protein after a three-step procedure involving (NH)SO fractionation, dialysis and anion exchange chromatography. Ftase showed optimum activity at pH 6.0 and temperature 50 °C. Ftase exhibited over 80% residual activity at pH range of 4.0-10.0 and ≈90% residual activity at temperature range of 40-60 °C for 6 h. Metal ion inhibitors Hg and Ag significantly inhibited Ftase activity at 1 mmol concentration. Ftase showed , and values of 79.51 mmol, 45.04 µmol min and 31.5 min, respectively, with a catalytic efficiency ( / ) of 396 µmol min for the substrate sucrose. HPLC-RI experiments identified the end products of fructosyltransferase activity as monomeric glucose, 1-kestose (GF), and 1,1-kestotetraose (GF). This study evaluates the feasibility of using this purified extracellular Ftase for the enzymatic synthesis of biofunctional fructooligosaccharides.