title: Synthesis of galactosyl glycerol from guar gum by transglycosylation of α-galactosidase from Aspergillus sp. MK14.
abstract: A guar gum-hydrolyzing strain, Aspergillus sp. MK14, secreted α-galactosidase selectively in liquid culture. Its α-galactosidase activity (0.820 U/ml) was much higher than its β-mannosidase and β-mannanase activities (0.027 and 0.050 U/ml, respectively). The molecular weight was estimated to be 59,000 Da by SDS-PAGE. The optimal pH was 5 and it was active from pH 2.2 to 6.2. The optimal temperature was 60 °C and the activity was stable below 50 °C. Enzyme activity toward melibiose was much lower than that with pNP-α-D-galactopyranoside. The activities toward 6(1)-α-D-galactosyl-mannobiose and 6(3),6(4)-α-D-galactosyl-mannopentaose were relatively high (86.2% and 48.4% relative to pNP-α-D-galactopyranoside, respectively). MK14 crude enzyme released only the monosaccharides, galactose and mannose (Gal/Man: 0.64) from guar gum. When glycerol was added to the reaction mixture, the transglycosylation proceeded efficiently, and the synthesis of galactosyl glycerol was 76.6 mg/g of guar gum. MK14 α-galactosidase could use guar gum as a good substrate (donor) in the transglycosylation.
authors.affiliation: Department of Marine Biotechnology, Fukuyama University, 1-985 Sanzo, Higashimura-cho, Fukuyama, Hiroshima 729-0292, Japan; Department of Life and Nutritional Science, Fukuyama University, 1-985 Sanzo, Higashimura-cho, Fukuyama, Hiroshima 729-0292, Japan. Electronic address: kurakake@fubac.fukuyama-u.ac.jp.
authors.forename: Masahiro
authors.initials: M
authors.lastname: Kurakake
authors.affiliation: Department of Life and Nutritional Science, Fukuyama University, 1-985 Sanzo, Higashimura-cho, Fukuyama, Hiroshima 729-0292, Japan.
authors.forename: Takumi
authors.initials: T
authors.lastname: Okumura
authors.affiliation: Department of Life and Nutritional Science, Fukuyama University, 1-985 Sanzo, Higashimura-cho, Fukuyama, Hiroshima 729-0292, Japan.
authors.forename: Youichirou
authors.initials: Y
authors.lastname: Morimoto
mesh_terms: D001230:Aspergillus / Q000201:enzymology*; D005685:Galactans / Q000378:metabolism*; D005690:Galactose / Q000737:chemistry* / Q000378:metabolism*; D005990:Glycerol / Q000737:chemistry* / Q000378:metabolism*; D006031:Glycosylation; D006863:Hydrogen-Ion Concentration; D008351:Mannans / Q000378:metabolism*; D053149:Plant Gums / Q000378:metabolism*; D000519:alpha-Galactosidase / Q000737:chemistry*
chemical_list: D005685:Galactans; D008351:Mannans; D053149:Plant Gums; C007894:guar gum; D000519:alpha-Galactosidase; D005990:Glycerol; D005690:Galactose
keywords: Galactosyl glycerol; Guar gum; Oligosaccharides; Transglycosylation; α-Galactosidase