Purification and properties ofβ-fructofuranosidase fromAureobasidium sp. ATCC 20524

Summary

Purification and properties of two β-fructofuranosidases, which produce 1-kestose (1^F-β-fructofuranosyl-sucrose) from sucrose, fromAureobasidium sp. ATCC 20524 are reported. The enzymes were purified to homogeneity by fractionations involving ethanol, calcium acetate and ammonium sulfate and DEAE-Cellulofine and Sephadex G-200 chromatography. Molecular weights of the enzymes were estimated to be about 318000 (P-1) and 346000 (P-2) daltons by gel filtration. The enzymes were glycoproteins that contained about 30% (w/v) (P-1) and 53% (w/v) (P-2) carbohydrate. The optimum pH for the enzymatic reactions were 4.5–5.5 (P-1) and 4.5–6 (P-2). The enzymes were stable over a wide pH range (4–9). The optimum reaction temperatures for both enzymes were 50–55°C and they retained more than 94% (P-1) and 98% (P-2) activities at 50°C after 15 min. TheK _m values for sucrose were 0.47 M (P-1) and 0.65 M (P-2). The enzymes were inhibited by mercury, copper and lead ions as well asp-chloromercuribenzoate.