Purification and properties of the beta-fructofuranosidase from Kluyveromyces fragilis.

The beta-fructofuranosidase from Kluyveromyces fragilis was purified to one band on electrophoresis by 3 different methods. Two of the preparations were found to be impure by isoelectric focusing. This demonstrates the need for more than one criteria of homogeneity when purifying this enzyme. The enzyme was found to be a glycoprotein, stable at 50 degrees C, with a pH optimum of 4.5. The cations Hg2+, Ag+, Cu2+ and Cd2+ exhibited a marked inhibition of the enzyme. Competitive inhibition was observed with the fructose analog 2,5-anhydro-D-mannitol suggesting that the enzyme is inhibited by the furanose form of fructose.