title: Kinetic properties and substrate inhibition of α-galactosidase from Aspergillus niger.
abstract: The recombinant AglB produced by Pichia pastoris exhibited substrate inhibition behavior for the hydrolysis of p-nitrophenyl α-galactoside, whereas it hydrolyzed the natural substrates, including galactomanno-oligosaccharides and raffinose family oligosaccharides, according to the Michaelian kinetics. These contrasting kinetic behaviors can be attributed to the difference in the dissociation constant of second substrate from the enzyme and/or to the ability of the leaving group of the substrates. The enzyme displays the grater kcat/Km values for hydrolysis of the branched α-galactoside in galactomanno-oligosaccharides than that of raffinose and stachyose. A sequence comparison suggested that AglB had a shallow active-site pocket, and it can allow to hydrolyze the branched α-galactosides, but not linear raffinose family oligosaccharides.
authors: a Research Faculty of Agriculture , Hokkaido University , Sapporo , Japan.
authors: Julan
authors: J
authors: Liao
authors: a Research Faculty of Agriculture , Hokkaido University , Sapporo , Japan.
authors: Masayuki
authors: M
authors: Okuyama
authors: a Research Faculty of Agriculture , Hokkaido University , Sapporo , Japan.
authors: Keigo
authors: K
authors: Ishihara
authors: a Research Faculty of Agriculture , Hokkaido University , Sapporo , Japan.
authors: Yoshinori
authors: Y
authors: Yamori
authors: a Research Faculty of Agriculture , Hokkaido University , Sapporo , Japan.
authors: Shigeo
authors: S
authors: Iki
authors: a Research Faculty of Agriculture , Hokkaido University , Sapporo , Japan.
authors: Takayoshi
authors: T
authors: Tagami
authors: a Research Faculty of Agriculture , Hokkaido University , Sapporo , Japan.
authors: Haruhide
authors: H
authors: Mori
authors: a Research Faculty of Agriculture , Hokkaido University , Sapporo , Japan.
authors: Seiya
authors: S
authors: Chiba
authors: a Research Faculty of Agriculture , Hokkaido University , Sapporo , Japan.
authors: Atsuo
authors: A
authors: Kimura
mesh_terms: D000595:Amino Acid Sequence / Q000235:genetics; D001234:Aspergillus niger / Q000201:enzymology* / Q000235:genetics; D020134:Catalytic Domain; D006868:Hydrolysis; D007700:Kinetics; D010843:Pichia / Q000235:genetics; D011887:Raffinose / Q000737:chemistry; D013379:Substrate Specificity; D000519:alpha-Galactosidase / Q000096:biosynthesis* / Q000737:chemistry* / Q000235:genetics
chemical_list: D000519:alpha-Galactosidase; D011887:Raffinose
keywords: glycoside hydrolase family 27; substrate inhibition; substrate specificity; α-galactosidase