Quezada-Calvillo, Roberto; Robayo-Torres, Claudia C; Opekun, Antone R; Sen, Partha; Ao, Zihua; Hamaker, Bruce R; Quaroni, Andrea; Brayer, Gary D; Wattler, Sigrid; Nehls, Michael C; Sterchi, Erwin E; Nichols, Buford L (2007). Contribution of mucosal maltase-glucoamylase activities to mouse small intestinal starch alpha-glucogenesis. Journal of nutrition, 137(7), pp. 1725-33. Bethesda, Md.: American Society for Nutrition
Full text not available from this repository. (Request a copy)Digestion of starch requires activities provided by 6 interactive small intestinal enzymes. Two of these are luminal endo-glucosidases named alpha-amylases. Four are exo-glucosidases bound to the luminal surface of enterocytes. These mucosal activities were identified as 4 different maltases. Two maltase activities were associated with sucrase-isomaltase. Two remaining maltases, lacking other identifying activities, were named maltase-glucoamylase. These 4 activities are better described as alpha-glucosidases because they digest all linear starch oligosaccharides to glucose. Because confusion persists about the relative roles of these 6 enzymes, we ablated maltase-glucoamylase gene expression by homologous recombination in Sv/129 mice. We assayed the alpha-glucogenic activities of the jejunal mucosa with and without added recombinant pancreatic alpha-amylase, using a range of food starch substrates. Compared with wild-type mucosa, null mucosa or alpha-amylase alone had little alpha-glucogenic activity. alpha-Amylase amplified wild-type and null mucosal alpha-glucogenesis. alpha-Amylase amplification was most potent against amylose and model resistant starches but was inactive against its final product limit-dextrin and its constituent glucosides. Both sucrase-isomaltase and maltase-glucoamylase were active with limit-dextrin substrate. These mucosal assays were corroborated by a 13C-limit-dextrin breath test. In conclusion, the global effect of maltase-glucoamylase ablation was a slowing of rates of mucosal alpha-glucogenesis. Maltase-glucoamylase determined rates of digestion of starch in normal mice and alpha-amylase served as an amplifier for mucosal starch digestion. Acarbose inhibition was most potent against maltase-glucoamylase activities of the wild-type mouse. The consortium of 6 interactive enzymes appears to be a mechanism for adaptation of alpha-glucogenesis to a wide range of food starches.
Item Type: |
Journal Article (Original Article) |
|---|---|
Division/Institute: |
04 Faculty of Medicine > Pre-clinic Human Medicine > Institute of Biochemistry and Molecular Medicine |
UniBE Contributor: |
Sterchi, Erwin-Ernst |
ISSN: |
0022-3166 |
ISBN: |
17585022 |
Publisher: |
American Society for Nutrition |
Language: |
English |
Submitter: |
Factscience Import |
Date Deposited: |
04 Oct 2013 14:53 |
Last Modified: |
05 Dec 2022 14:16 |
PubMed ID: |
17585022 |
Web of Science ID: |
000247972900004 |
URI: |
https://boris.unibe.ch/id/eprint/22694 (FactScience: 36057) |
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