title: Structure of the cyclic glucan produced from amylopectin by Bacillus stearothermophilus branching enzyme.
abstract: The thermostable branching enzyme (BE, EC 2.4.1.18) from Bacillus stearothermophilus TRBE14 produces large cyclic glucans from waxy rice amylopectin similar to those obtained from amylose as described elsewhere [H. Takata, T. Takaha, S. Okada. M. Takagi, and T. Imanaka, J. Bacteriol., 178 (1996) 1600-1606]. The structure of the product (P-1) from the late-stage reaction was analyzed in detail. The weight-average degree of polymerization (dpw) of P-1 was 900. Its chain-length distribution was not significantly changed compared with that of amylopectin, although the amount of long chains (dp > 38) was slightly decreased. The cyclic component of P-1, which was isolated by the extensive action of glucoamylase, had dpw of 49. Three point five alpha-1,6 linkages were directly involved in the formation of the ring structure with several non-cyclic side chains linked to the ring. Based on these results, the action and new roles of BE are discussed.
authors.affiliation: Biochemical Research Laboratory, Ezaki Glico Co., Ltd., Osaka, Japan.
authors.forename: H
authors.initials: H
authors.lastname: Takata
authors.forename: T
authors.initials: T
authors.lastname: Takaha
authors.forename: S
authors.initials: S
authors.lastname: Okada
authors.forename: S
authors.initials: S
authors.lastname: Hizukuri
authors.forename: M
authors.initials: M
authors.lastname: Takagi
authors.forename: T
authors.initials: T
authors.lastname: Imanaka
mesh_terms: D015061:1,4-alpha-Glucan Branching Enzyme / Q000378:metabolism*; D000687:Amylopectin / Q000737:chemistry / Q000378:metabolism*; D000688:Amylose / Q000737:chemistry; D002850:Chromatography, Gel; D002851:Chromatography, High Pressure Liquid; D004795:Enzyme Stability; D004926:Escherichia coli / Q000201:enzymology / Q000235:genetics; D001411:Geobacillus stearothermophilus / Q000201:enzymology*; D005087:Glucan 1,4-alpha-Glucosidase / Q000378:metabolism; D007517:Isoamylase / Q000378:metabolism; D008956:Models, Chemical; D011134:Polysaccharides / Q000737:chemistry*; D000516:alpha-Amylases / Q000378:metabolism
chemical_list: D011134:Polysaccharides; D000688:Amylose; D000687:Amylopectin; D015061:1,4-alpha-Glucan Branching Enzyme; D000516:alpha-Amylases; D005087:Glucan 1,4-alpha-Glucosidase; D007517:Isoamylase