Jai-Sik Hong

Purification and properties of β-fructofuranosidase from Aspergillus niger

Abstract Three forms of inulase were purified from Aspergillus niger by ultrafiltration, DEAE-Trisacryl chromatography Sephadex G-150 gel filtration, and preparative isoelectric focusing. The isoelectric focusing resolved inulase into three peaks with isoelectric points of 4.5, 4.9 and 5.2. Among them, peaks II and III were purified to homogeneity as a single band on an analytical isoelectric focusing gel. These peaks represented glycoproteins with similar molecular weights, about 3·10 5 , and appeared to consist of four identical subunits. On the basis of molecular weight, subunit, amino acid analysis, chemical modification and fluorescence spectrum, the overall molecular characteristics of the three forms were similar. However, the three forms exhibited distinctly different kinetic constants. The enzyme splits β-2,1 linkage of sucrose and straight chain oligo- and polyfructosides of the insulin type, by endwise removal of fructosyl units.