title: Evidence of native starch degradation with human small intestinal maltase-glucoamylase (recombinant).
abstract: Action of human small intestinal brush border carbohydrate digesting enzymes is thought to involve only final hydrolysis reactions of oligosaccharides to monosaccharides. In vitro starch digestibility assays use fungal amyloglucosidase to provide this function. In this study, recombinant N-terminal subunit enzyme of human small intestinal maltase-glucoamylase (rhMGAM-N) was used to explore digestion of native starches from different botanical sources. The susceptibilities to enzyme hydrolysis varied among the starches. The rate and extent of hydrolysis of amylomaize-5 and amylomaize-7 into glucose were greater than for other starches. Such was not observed with fungal amyloglucosidase or pancreatic alpha-amylase. The degradation of native starch granules showed a surface furrowed pattern in random, radial, or tree-like arrangements that differed substantially from the erosion patterns of amyloglucosidase or alpha-amylase. The evidence of raw starch granule degradation with rhMGAM-N indicates that pancreatic alpha-amylase hydrolysis is not a requirement for native starch digestion in the human small intestine.
authors.affiliation: Whistler Center for Carbohydrate Research and Department of Food Science, 745 Agriculture Mall Drive, Purdue University, West Lafayette, IN 47907-2009, USA.
authors.forename: Zihua
authors.initials: Z
authors.lastname: Ao
authors.forename: Roberto
authors.initials: R
authors.lastname: Quezada-Calvillo
authors.forename: Lyann
authors.initials: L
authors.lastname: Sim
authors.forename: Buford L
authors.initials: BL
authors.lastname: Nichols
authors.forename: David R
authors.initials: DR
authors.lastname: Rose
authors.forename: Erwin E
authors.initials: EE
authors.lastname: Sterchi
authors.forename: Bruce R
authors.initials: BR
authors.lastname: Hamaker
mesh_terms: D004063:Digestion; D005087:Glucan 1,4-alpha-Glucosidase / Q000378:metabolism; D006801:Humans; D006868:Hydrolysis; D007421:Intestine, Small / Q000201:enzymology*; D007700:Kinetics; D002365:Manihot; D010179:Pancreas / Q000201:enzymology; D011994:Recombinant Proteins / Q000378:metabolism; D012233:Rhizopus / Q000201:enzymology; D013213:Starch / Q000378:metabolism*; D003313:Zea mays; D000516:alpha-Amylases / Q000378:metabolism; D000520:alpha-Glucosidases / Q000378:metabolism*
chemical_list: D011994:Recombinant Proteins; D013213:Starch; D000516:alpha-Amylases; D000520:alpha-Glucosidases; D005087:Glucan 1,4-alpha-Glucosidase