Abstract: In this study, the fructosyltransferase gene fru from Aspergillus niger was heterologously expressed with pET28a plasmid in Escherichia coli BL21 (DE3). The enzymatic properties of recombinant fructosyltransferase were analyzed after purification. The results showed that the activity of recombinant fructosyltransferase was 18.4 U/mg, and the specific activity was 706.6 U/mg after purification. The optimum temperature and pH of recombinant fructosyltransferase were 45℃ and 5.5, respectively. The Km, Vmax and kcat values of recombinant fructosyltransferase were 1.8 mol/L, 8.2 mmol/(L·min) and 2558.5 s-1, respectively. On addition of 50.0 g/L and 100.0 g/L glucose, the Ki values were 3.4 mol/L and 0.3 mol/L, respectively. The recombinant fructosyltransferase was significantly activated by 1.0 mmol/L Co2+, Mn2+, or Zn2+.

Key words: fructosyltransferase, Escherichia coli, expression, enzymatic property