title: Structure of branching enzyme- and amylomaltase modified starch produced from well-defined amylose to amylopectin substrates.
abstract: Thermostable branching enzyme (BE, EC 2.4.1.18) from Rhodothermus obamensis in combination with amylomaltase (AM, EC 2.4.1.25) from Thermus thermophilus was used to modify starch structure exploring potentials to extensively increase the number of branch points in starch. Amylose is an important constituent in starch and the effect of amylose on enzyme catalysis was investigated using amylose-only barley starch (AO) and waxy maize starch (WX) in well-defined ratios. All products were analysed for amylopectin chain length distribution, α-1,6 glucosidic linkages content, molar mass distribution and digestibility by using rat intestinal α-glucosidases. For each enzyme treatment series, increased AO content resulted in a higher rate of α-1,6 glucosidic linkage formation but as an effect of the very low initial branching of the AO, the final content of α-1,6 glucosidic linkages was slightly lower as compared to the high amylopectin substrates. However, an increase specifically in short chains was produced at high AO levels. The molar mass distribution for the enzyme treated samples was lower as compared with substrate WX and AO, indicating the presence of hydrolytic activity as well as cyclisation of the substrate. For all samples, increased amylose substrate showed decreased α- and β-amylolysis. Surprisingly, hydrolysis with rat intestinal α-glucosidases was higher with increasing α-1,6 glucosidic linkage content and decreasing M¯w indicating that steric hindrance towards the α-glucosidases was directed by the molar mass rather that the branching density of the glucan per se. Our data demonstrate that a higher amylose content in the substrate starch efficiently produces α-1,6 glucosidic linkages and that the present of amylose generates a higher M¯w and more resistant product than amylopectin. The combination of BE→AM→BE provided somewhat more resistant α-glucan products as compared to BE alone.
authors: School of Food Technology, Institute of Agricultural Technology, Suranaree University of Technology, Nakhon Ratchasima 30000, Thailand; Department of Plant and Environmental Sciences, Faculty of Sciences, University of Copenhagen, Frederiksberg C 1871, Denmark.
authors: Waraporn
authors: W
authors: Sorndech
authors: Department of Plant and Environmental Sciences, Faculty of Sciences, University of Copenhagen, Frederiksberg C 1871, Denmark; Department of Molecular Biology and Genetics, Aarhus University, Forsøgsvej 1, 4200 Slagelse, Denmark.
authors: Domenico
authors: D
authors: Sagnelli
authors: Technical University of Denmark, Department of Chemistry, Kemitorvet, 2800 Kgs. Lyngby, Denmark.
authors: Sebastian
authors: S
authors: Meier
authors: Carlsberg Research Laboratory, Copenhagen V 1799, Denmark.
authors: Anita M
authors: AM
authors: Jansson
authors: Department of Food Science & Biotechnology, College of BioNano Technology, Gachon University, Seongnam 461-701, South Korea.
authors: Byung-Hoo
authors: BH
authors: Lee
authors: Whistler Center for Carbohydrate Research, Department of Food Science, Purdue University, IN 47907, United States.
authors: Bruce R
authors: BR
authors: Hamaker
authors: UR126 8 Biopolymères Interactions Assemblages, INRA, F-44316 Nantes, France.
authors: Agnès
authors: A
authors: Rolland-Sabaté
authors: Department of Molecular Biology and Genetics, Aarhus University, Forsøgsvej 1, 4200 Slagelse, Denmark.
authors: Kim H
authors: KH
authors: Hebelstrup
authors: School of Food Technology, Institute of Agricultural Technology, Suranaree University of Technology, Nakhon Ratchasima 30000, Thailand. Electronic address: s-tongta@g.sut.ac.th.
authors: Sunanta
authors: S
authors: Tongta
authors: Department of Plant and Environmental Sciences, Faculty of Sciences, University of Copenhagen, Frederiksberg C 1871, Denmark. Electronic address: abl@life.ku.dk.
authors: Andreas
authors: A
authors: Blennow
mesh_terms: D000687:Amylopectin / Q000737:chemistry*; D000688:Amylose / Q000737:chemistry*; D001426:Bacterial Proteins / Q000737:chemistry*; D006004:Glycogen Debranching Enzyme System / Q000737:chemistry*; D045245:Rhodothermus / Q000201:enzymology*; D016963:Thermus thermophilus / Q000201:enzymology*
chemical_list: D001426:Bacterial Proteins; D006004:Glycogen Debranching Enzyme System; D000688:Amylose; D000687:Amylopectin; C020569:4 alpha-glucanotransferase
keywords: Amylomaltase; Amylose content; Branching enzyme; Starch degradation