title: Branch pattern of starch internal structure influences the glucogenesis by mucosal Nt-maltase-glucoamylase.
abstract: To produce sufficient amounts of glucose from food starch, both α-amylase and mucosal α-glucosidases are required. We found previously that the digestion rate of starch is influenced by its susceptibility to mucosal α-glucosidases. In the present study, six starches and one glycogen were pre-hydrolyzed by α-amylase for various time periods, and then further hydrolyzed with the mucosal α-glucosidase, the N-terminal subunit of maltase-glucoamylase (Nt-MGAM), to generate free glucose. Results showed that α-amylase amplified the Nt-MGAM glucogenesis, and that the amplifications differed in various substrates. The amount of branches within α-amylase hydrolysate substrates was highly related to the rate of Nt-MGAM glucogenesis. After de-branching, the hydrolysates showed three fractions, Fraction 1, 2, and 3, in size exclusion chromatographs. We found that the α-amylase hydrolysates with higher quantity of the Fraction 3 (molecules with relatively short chain-length) and shorter average chain-length of this fraction had lower rates of Nt-MGAM glucogenesis. This study revealed that the branch pattern of α-amylase hydrolysates modulates glucose release by Nt-MGAM. It further supported the hypothesis that the internal structure of starch affects its digestibility at the mucosal α-glucosidase level.
authors.affiliation: Whistler Center for Carbohydrate Research, Department of Food Science, Purdue University, 745 Agriculture Mall Drive, West Lafayette, IN 47907-2009, USA. Electronic address: amylin@purdue.edu.
authors.forename: Amy Hui-Mei
authors.initials: AH
authors.lastname: Lin
authors.affiliation: Whistler Center for Carbohydrate Research, Department of Food Science, Purdue University, 745 Agriculture Mall Drive, West Lafayette, IN 47907-2009, USA. Electronic address: zihua.ao@mjn.com.
authors.forename: Zihua
authors.initials: Z
authors.lastname: Ao
authors.affiliation: USDA, Agricultural Research Service, Children's Nutrition Research Center and Department of Pediatrics, Baylor College of Medicine, 1100 Bates Street, Houston, TX 77030-300, USA. Electronic address: rqc@uaslp.mx.
authors.forename: Roberto
authors.initials: R
authors.lastname: Quezada-Calvillo
authors.affiliation: USDA, Agricultural Research Service, Children's Nutrition Research Center and Department of Pediatrics, Baylor College of Medicine, 1100 Bates Street, Houston, TX 77030-300, USA. Electronic address: blnjr@sbcglobal.net.
authors.forename: Buford L
authors.initials: BL
authors.lastname: Nichols
authors.affiliation: Department of Financial and Computational Mathematics, Providence University, Taichung City 436, Taiwan, ROC. Electronic address: ctlin@pu.edu.tw.
authors.forename: Chi-Tien
authors.initials: CT
authors.lastname: Lin
authors.affiliation: Whistler Center for Carbohydrate Research, Department of Food Science, Purdue University, 745 Agriculture Mall Drive, West Lafayette, IN 47907-2009, USA. Electronic address: hamakerb@purdue.edu.
authors.forename: Bruce R
authors.initials: BR
authors.lastname: Hamaker
mesh_terms: D004063:Digestion; D005947:Glucose / Q000378:metabolism*; D006003:Glycogen / Q000378:metabolism; D006801:Humans; D007413:Intestinal Mucosa / Q000201:enzymology*; D013213:Starch / Q000737:chemistry* / Q000378:metabolism*; D000516:alpha-Amylases / Q000378:metabolism; D000520:alpha-Glucosidases / Q000378:metabolism*
chemical_list: D013213:Starch; D006003:Glycogen; D000516:alpha-Amylases; D000520:alpha-Glucosidases; D005947:Glucose
keywords: Glycemia; Maltase-glucoamylase; Mucosal α-glucosidase; Starch branch; Starch digestibility; α-1→6 linkage