title: Glucoamylase originating from Schwanniomyces occidentalis is a typical alpha-glucosidase.
abstract: A starch-hydrolyzing enzyme from Schwanniomyces occidentalis has been reported to be a novel glucoamylase, but there is no conclusive proof that it is glucoamylase. An enzyme having the hydrolytic activity toward soluble starch was purified from a strain of S. occidentalis. The enzyme showed high catalytic efficiency (k(cat)/K(m)) for maltooligosaccharides, compared with that for soluble starch. The product anomer was alpha-glucose, differing from glucoamylase as a beta-glucose producing enzyme. These findings are striking characteristics of alpha-glucosidase. The DNA encoding the enzyme was cloned and sequenced. The primary structure deduced from the nucleotide sequence was highly similar to mold, plant, and mammalian alpha-glucosidases of alpha-glucosidase family II and other glucoside hydrolase family 31 enzymes, and the two regions involved in the catalytic reaction of alpha-glucosidases were conserved. These were no similarities to the so-called glucoamylases. It was concluded that the enzyme and also S. occidentalis glucoamylase, had been already reported, were typical alpha-glucosidases, and not glucoamylase.
authors.affiliation: Division of Applied Bioscience, Graduate School of Agriculture, Hokkaido University, Sapporo, Japan.
authors.forename: Fumiaki
authors.initials: F
authors.lastname: Sato
authors.forename: Masayuki
authors.initials: M
authors.lastname: Okuyama
authors.forename: Hiroyuki
authors.initials: H
authors.lastname: Nakai
authors.forename: Haruhide
authors.initials: H
authors.lastname: Mori
authors.forename: Atsuo
authors.initials: A
authors.lastname: Kimura
authors.forename: Seiya
authors.initials: S
authors.lastname: Chiba
mesh_terms: D020134:Catalytic Domain; D003001:Cloning, Molecular; D017124:Conserved Sequence; D005656:Fungal Proteins / Q000235:genetics* / Q000378:metabolism; D005087:Glucan 1,4-alpha-Glucosidase / Q000235:genetics* / Q000378:metabolism; D006868:Hydrolysis; D007700:Kinetics; D016415:Sequence Alignment; D013213:Starch / Q000378:metabolism; D000520:alpha-Glucosidases / Q000378:metabolism*
chemical_list: D005656:Fungal Proteins; D013213:Starch; D000520:alpha-Glucosidases; D005087:Glucan 1,4-alpha-Glucosidase