title: Purification and characterization of highly branched α-glucan-producing enzymes from Paenibacillus sp. PP710.
abstract: Highly branched α-glucan molecules exhibit low digestibility for α-amylase and glucoamylase, and abundant in α-(1→3)-, α-(1→6)-glucosidic linkages and α-(1→6)-linked branch points where another glucosyl chain is initiated through an α-(1→3)-linkage. From a culture supernatant of Paenibacillus sp. PP710, we purified α-glucosidase (AGL) and α-amylase (AMY), which were involved in the production of highly branched α-glucan from maltodextrin. AGL catalyzed the transglucosylation reaction of a glucosyl residue to a nonreducing-end glucosyl residue by α-1,6-, α-1,4-, and α-1,3-linkages. AMY catalyzed the hydrolysis of the α-1,4-linkage and the intermolecular or intramolecular transfer of maltooligosaccharide like cyclodextrin glucanotransferase (CGTase). It also catalyzed the transfer of an α-1,4-glucosyl chain to a C3- or C4-hydroxyl group in the α-1,4- or α-1,6-linked nonreducing-end residue or the α-1,6-linked residue located in the other chains. Hence AMY was regarded as a novel enzyme. We think that the mechanism of formation of highly branched α-glucan from maltodextrin is as follows: α-1,6- and α-1,3-linked residues are generated by the transglucosylation of AGL at the nonreducing ends of glucosyl chains. Then AMY catalyzes the transfer of α-1,4-chains to C3- or C4-hydroxyl groups in the α-1,4- or α-1,6-linked residues generated by AGL. Thus the concerted reactions of both AGL and AMY are necessary to produce the highly branched α-glucan from maltodextrin.
authors.affiliation: Glycoscience Institute, Research Center, Hayashibara Biochemical Laboratories, Inc., Naka-ku, Okayama, Japan. tsusaki@hayashibara.co.jp
authors.forename: Keiji
authors.initials: K
authors.lastname: Tsusaki
authors.forename: Hikaru
authors.initials: H
authors.lastname: Watanabe
authors.forename: Takuo
authors.initials: T
authors.lastname: Yamamoto
authors.forename: Tomoyuki
authors.initials: T
authors.lastname: Nishimoto
authors.forename: Hiroto
authors.initials: H
authors.lastname: Chaen
authors.forename: Shigeharu
authors.initials: S
authors.lastname: Fukuda
mesh_terms: D055162:Biocatalysis; D002240:Carbohydrate Sequence; D002850:Chromatography, Gel; D002851:Chromatography, High Pressure Liquid; D004591:Electrophoresis, Polyacrylamide Gel; D005936:Glucans / Q000096:biosynthesis*; D006031:Glycosylation; D009844:Oligosaccharides / Q000378:metabolism; D025942:Oligosaccharides, Branched-Chain / Q000096:biosynthesis*; D010084:Oxidation-Reduction; D056507:Paenibacillus / Q000737:chemistry / Q000201:enzymology*; D011134:Polysaccharides / Q000378:metabolism*; D000516:alpha-Amylases / Q000302:isolation & purification* / Q000378:metabolism; D000520:alpha-Glucosidases / Q000302:isolation & purification* / Q000378:metabolism
chemical_list: D005936:Glucans; D009844:Oligosaccharides; D025942:Oligosaccharides, Branched-Chain; D011134:Polysaccharides; C021705:maltooligosaccharides; C008315:maltodextrin; D000516:alpha-Amylases; D000520:alpha-Glucosidases