title: A novel glucanotransferase from a Bacillus circulans strain that produces a cyclomaltopentaose cyclized by an alpha-1,6-linkage.
abstract: A novel glucanotransferase, involved in the synthesis of a cyclomaltopentaose cyclized by an alpha-1,6-linkage [ICG5; cyclo-{-->6)-alpha-D-Glcp-(1-->4)-alpha-D-Glcp-(1-->4)-alpha-D-Glcp-(1-->4)-alpha-D-Glcp-(1-->4)-alpha-D-Glcp-(1-->}], from starch, was purified to homogeneity from the culture supernatant of Bacillus circulans AM7. The pI was estimated to be 7.5. The molecular mass of the enzyme was estimated to be 184 kDa by gel filtration and 106 kDa by SDS-PAGE. These results suggest that the enzyme forms a dimer structure. It was most active at pH 4.5 to 8.0 at 50 degrees C, and stable from pH 4.5 to 9.0 at up to 35 degrees C. The addition of 1 mM Ca(2+) enhanced the thermal stability of the enzyme up to 40 degrees C. It acted on maltooligosaccharides that have degrees of polymerization of 3 or more, amylose, and soluble starch, to produce ICG5 by an intramolecular alpha-1,6-glycosyl transfer reaction. It also catalyzed the transfer of part of a linear oligosaccharide to another oligosaccharide by an intermolecular alpha-1,4-glycosyl transfer reaction. Thus the ICG5-forming enzyme was found to be a novel glucanotransferase. We propose isocyclomaltooligosaccharide glucanotransferase (IGTase) as the trivial name of this enzyme.
authors.affiliation: Glycoscience Institute, Research Center, Hayashibara Biochemical Laboratories, Inc., Okayama, Japan. h-watanabe@hayashibara.co.jp
authors.forename: Hikaru
authors.initials: H
authors.lastname: Watanabe
authors.forename: Tomoyuki
authors.initials: T
authors.lastname: Nishimoto
authors.forename: Kazuhisa
authors.initials: K
authors.lastname: Mukai
authors.forename: Michio
authors.initials: M
authors.lastname: Kubota
authors.forename: Hiroto
authors.initials: H
authors.lastname: Chaen
authors.forename: Shigeharu
authors.initials: S
authors.lastname: Fukuda
mesh_terms: D000595:Amino Acid Sequence; D000688:Amylose / Q000737:chemistry; D001407:Bacillus / Q000201:enzymology*; D003500:Cyclization; D019281:Dimerization; D005936:Glucans / Q000737:chemistry; D005964:Glucosyltransferases / Q000737:chemistry* / Q000235:genetics / Q000302:isolation & purification; D006863:Hydrogen-Ion Concentration; D008969:Molecular Sequence Data; D009844:Oligosaccharides / Q000096:biosynthesis* / Q000737:chemistry; D013379:Substrate Specificity; D013696:Temperature; D013997:Time Factors
chemical_list: D005936:Glucans; D009844:Oligosaccharides; C514763:cyclo(-6-glucopyranosyl-1-4-glucopyranosyl-1-4-glucopyranosyl-1-4-glucopyranosyl-1-4-glucopyranosyl-1); C031146:maltoheptaose; D000688:Amylose; D005964:Glucosyltransferases; C514764:isocyclomaltooligosaccharide glucanotransferase, Bacillus circulans