title: Purification and characterization of a fructosyltransferase from onion bulbs and its key role in the synthesis of fructo-oligosaccharides in vivo.
abstract: A fructosyltransferase that transfers the terminal (2 --> 1)-beta-linked D-fructosyl group of fructo-oligosaccharides (1(F)(1-beta-D-fructofuranosyl)(n) sucrose, n >/= 1) to HO-6 of the glucosyl residue and HO-1 of the fructosyl residue of similar saccharides (1(F)(1-beta-D-fructofuranosyl)(m) sucrose, m >/= 0) has been purified from an extract of the bulbs of onion (Allium cepa). Successive column chromatography using DEAE-Sepharose CL-6B, Toyopearl HW65, Toyopearl HW55, DEAE-Sepharose CL-6B (2nd time), Sephadex G-100, Concanavalin A Sepharose, and Toyopearl HW-65 (2nd time) were applied for protein purification. The general properties of the enzyme, were as follows: molecular masses of 66 kDa (gel filtration chromatography), and of 52 kDa and 25 kDa (SDS-PAGE); optimum pH of c. 5.68, stable at 20-40 degrees C for 15 min; stable in a range of pH 5.30-6.31 at 30 degrees C for 30 min, inhibited by Hg(2+), Ag(+), p-chloromercuribenzoic acid (p-CMB) and sodium dodecyl sulfate (SDS), activated by sodium deoxycholate, Triton X-100 and Tween-80. The amino acid sequence of the N-terminus moiety of the 52-kDa polypeptide was ADNEFPWTNDMLAWQRCGFHFRTVRNYMNDPSGPMYYKGWYHLFYQHNKDFAYXG and the amino acid sequence from the N-terminus of the 25-kDa polypeptide was ADVGYXCSTSGGAATRGTLGPFGLL VLANQDLTENTATYFYVSKGTDGALRTHFCQDET. The enzyme tentatively classified as fructan: fructan 6(G)-fructosyltransferase (6G-FFT). The enzyme is proposed to play an important role in the synthesis of inulin and inulinneo-series fructo-oligosaccharides in onion bulbs.
authors.affiliation: Department of Food and Nutrition Sciences, Graduate School of Dairy Science Research, Rakuno Gakuen University, 582 Bunkyodai, Midorimachi, Ebetsu, Hokkaido 069-8501, Japan.
authors.forename: Masaki
authors.initials: M
authors.lastname: Fujishima
authors.forename: Hideki
authors.initials: H
authors.lastname: Sakai
authors.forename: Keiji
authors.initials: K
authors.lastname: Ueno
authors.forename: Natsuko
authors.initials: N
authors.lastname: Takahashi
authors.forename: Shuichi
authors.initials: S
authors.lastname: Onodera
authors.forename: Noureddine
authors.initials: N
authors.lastname: Benkeblia
authors.forename: Norio
authors.initials: N
authors.lastname: Shiomi
mesh_terms: D000595:Amino Acid Sequence; D002240:Carbohydrate Sequence; D004795:Enzyme Stability; D019270:Fructosamine / Q000378:metabolism; D006602:Hexosyltransferases / Q000302:isolation & purification* / Q000378:metabolism*; D006863:Hydrogen-Ion Concentration; D008969:Molecular Sequence Data; D015394:Molecular Structure; D009844:Oligosaccharides / Q000096:biosynthesis* / Q000737:chemistry; D019697:Onions / Q000201:enzymology*; D017386:Sequence Homology, Amino Acid; D013379:Substrate Specificity; D013696:Temperature; D013997:Time Factors
chemical_list: D009844:Oligosaccharides; D019270:Fructosamine; D006602:Hexosyltransferases; C105700:fructan - fructan 6G-fructosyltransferase