Partial Purification and Characterization of Exoinulinase from Kluyveromyces marxianus YS-1 for Preparation of High-Fructose Syrup

An extracellular exoinulinase (2,1-β-D fructan fructanohydrolase, EC 3.2.1.7), which catalyzes the hydrolysis of inulin into fructose and glucose, was purified 23.5-fold by ethanol precipitation, followed by Sephadex G-100 gel permeation from a cell-free extract of Kluyveromyces marxianus YS-1. The partially purified enzyme exhibited considerable activity between pH 5 to 6, with an optimum pH of 5.5, while it remained stable (100%) for 3 h at the optimum temperature of 50℃. Mn²+ and Ca²+ produced a 2.4-fold and 1.2-fold enhancement in enzyme activity, whereas Hg²+ and Ag²+ completely inhibited the inulinase.