Purification and characterisation of 6 G-fructosyltransferase from the roots of asparagus ( Asparagus officinalis L.)

Abstract

A fructosyltransferase that catalyses the transfer of the terminal (2 → 1)-β-linked d-fructosyl group of fructo-oligosaccharides [1 F(1-β- d-fructofuranosyl) m sucrose, m > 0] to HO-6 of the glucosyl group of similar saccharides [1 F(1-β- d-fructofuranosyl) n sucrose, n > 0] has been purified (760-fold) from an extract of the roots of asparagus ( Asparagus officinalis L.) by successive fractionation with ammonium sulfate, treatment with calcium phosphate gel, and then chromatography on octyl-Sepharose, DEAE-cellulose, Sephadex G-200, and raffinose-coupled Sepharose 6B. The enzyme, tentatively termed 6 G-fructosyltransferase, was homogeneous in disc electrophoresis, had a mol. wt. of ~69,000 and an optimum pH of ~5.5, was stable at pH 5.0–6.0 on heating for 20 mins at 45° and for 10 min at 20–37°, and was inhibited by Hg 2+, p-chloromercuribenzoate, and Ag +.