title: Purification and characterization of a O-methyltransferase capable of methylating 2-hydroxy-3-alkylpyrazine from Vitis vinifera L. (cv. Cabernet Sauvignon).
abstract: An S-adenosyl-L-methionine-dependent O-methyltransferase capable of methylating 2-hydroxy-3-alkylpyrazine (HP) was purified 7,300-fold to apparent homogeneity with an 8.2% overall recovery from Vitis vinifera L. (cv. Cabernet Sauvignon) through a purification procedure including column chromatography on DEAE-Sepharose FF, Ether-5PW, hydroxyapatite, G2000SW(XL), and DEAE-5PW. The relative molecular mass of the native enzyme estimated on gel permeation chromatography was 85 kDa, and the subunit molecular mass was estimated to be 41 kDa on SDS-polyacrylamide gel electrophoresis. The enzyme also methylates caffeic acid. The Vmax for IBHP and caffeic acid were 0.73 and 175 pkatals/mg, respectively, and the respective Km for IBHP and caffeic acid were 0.30 and 0.032 mm. The optimum pH for IBHP (8.5) was different from that for caffeic acid (7.5).
authors.affiliation: National Research Institute of Brewing, Higashihiroshima, Japan. hasidume@nrib.go.jp
authors.forename: K
authors.initials: K
authors.lastname: Hashizume
authors.forename: K
authors.initials: K
authors.lastname: Tozawa
authors.forename: Y
authors.initials: Y
authors.lastname: Hiraga
authors.forename: I
authors.initials: I
authors.lastname: Aramaki
mesh_terms: D000595:Amino Acid Sequence; D002848:Chromatography, DEAE-Cellulose; D002850:Chromatography, Gel; D002851:Chromatography, High Pressure Liquid; D004591:Electrophoresis, Polyacrylamide Gel; D006863:Hydrogen-Ion Concentration; D007700:Kinetics; D008969:Molecular Sequence Data; D008970:Molecular Weight; D011497:Protein O-Methyltransferase / Q000302:isolation & purification* / Q000378:metabolism; D011719:Pyrazines / Q000378:metabolism*; D017386:Sequence Homology, Amino Acid; D027843:Vitis / Q000201:enzymology*
chemical_list: D011719:Pyrazines; D011497:Protein O-Methyltransferase