Mucosal C‐terminal maltase‐glucoamylase hydrolyzes large size starch digestion products that may contribute to rapid postprandial glucose generation

Lee, Byung‐Hoo; Lin, Amy Hui‐Mei; Nichols, Buford L.; Jones, Kyra; Rose, David R.; Quezada‐Calvillo, Roberto; Hamaker, Bruce R.

doi:10.1002/mnfr.201300599

Cited by 41 publications

(33 citation statements)

References 45 publications

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“…These enzymes are located close to the active transport sites for monosaccharides (Eliasson, ). The four enzymes, distinguished by their N‐ and C‐terminal subunits, are ntMGAM (maltase), ctMGAM (glucoamylase), ntSI (isomaltase), and ctSI (sucrase) (Lee et al, ). The functional differences among these enzymes reflect their degree of specificity for a particular substrate or glycosidic linkage (Lee et al, ).…”

Section: Challenges To the Starch Digestion Hypothesis For Amy1 Cnvmentioning

confidence: 99%

“…The four enzymes, distinguished by their N‐ and C‐terminal subunits, are ntMGAM (maltase), ctMGAM (glucoamylase), ntSI (isomaltase), and ctSI (sucrase) (Lee et al, ). The functional differences among these enzymes reflect their degree of specificity for a particular substrate or glycosidic linkage (Lee et al, ). Glucoamylase has high specificity for the α‐1,4 bonds at the nonreducing terminus of unbranched chain glucosyl units; maltase hydrolyzes α −1,4 bonds in both starch oligosaccharides, and disaccharide maltose.…”

Section: Challenges To the Starch Digestion Hypothesis For Amy1 Cnvmentioning

confidence: 99%

“…Furthermore, recent studies have shown that brush border glucoamylase works together with α‐amylase at the initial stage of starch digestion to produce maltodextrins and glucose (Dhital, Lin, Hamaker, Gidley, & Muniandy, ; Lee et al, ). Importantly, glucoamylase can act on whole, nonhydrolyzed starches directly (Mochizuki, Honma, Shimada, & Goda, ) and thus α‐amylase hydrolysis is not a required step in starch digestion (Ao et al, ).…”

Section: Challenges To the Starch Digestion Hypothesis For Amy1 Cnvmentioning

confidence: 99%

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Rethinking the starch digestion hypothesis for AMY1 copy number variation in humans

Fernández

Wiley

2017

American J Phys Anthropol

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Alpha-amylase exists across taxonomic kingdoms with a deep evolutionary history of gene duplications that resulted in several α-amylase paralogs. Copy number variation (CNV) in the salivary α-amylase gene (AMY1) exists in many taxa, but among primates, humans appear to have higher average AMY1 copies than nonhuman primates. Additionally, AMY1 CNV in humans has been associated with starch content of diets, and one known function of α-amylase is its involvement in starch digestion. Thus high AMY1 CNV is considered to result from selection favoring more efficient starch digestion in the Homo lineage. Here, we present several lines of evidence that challenge the hypothesis that increased AMY1 CNV is an adaptation to starch consumption. We observe that α- amylase plays a very limited role in starch digestion, with additional steps required for starch digestion and glucose metabolism. Specifically, we note that α-amylase hydrolysis only produces a minute amount of free glucose with further enzymatic digestion and glucose absorption being rate-limiting steps for glucose availability. Indeed α-amylase is nonessential for starch digestion since sucrase-isomaltase and maltase-glucoamylase can hydrolyze whole starch granules while releasing glucose. While higher AMY1 CN and CNV among human populations may result from natural selection, existing evidence does not support starch digestion as the major selective force. We report that in humans α-amylase is expressed in several other tissues where it may have potential roles of evolutionary significance.

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Section: Challenges To the Starch Digestion Hypothesis For Amy1 Cnvmentioning

confidence: 99%

Section: Challenges To the Starch Digestion Hypothesis For Amy1 Cnvmentioning

confidence: 99%

Section: Challenges To the Starch Digestion Hypothesis For Amy1 Cnvmentioning

confidence: 99%

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Rethinking the starch digestion hypothesis for AMY1 copy number variation in humans

Fernández

Wiley

2017

American J Phys Anthropol

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“…Nt‐SI (also known as isomaltase) and Ct‐SI (also known as sucrase) can also digest branched glucans and sucrose, respectively. We have shown that α‐glucosidase can directly digest large glucans, such as starch molecules, to glucose, and that Ct‐MGAM alone can quickly release approximately 80% of glucose from gelatinized starch . Each of the α‐glucosidases has special preference in substrate structure and digests starch molecules or α‐amylase hydrolysates differently .…”

Section: Starch Digestive Enzymes In the Young Childmentioning

confidence: 99%

The digestion of complementary feeding starches in the young child

Lin

Nichols

2017

Starch Stärke

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Digestible glycemic carbohydrates are an important energy source to support the rapid growth and development of young children. The aim of this comprehensive review is to present up-to-date knowledge of starch digestion in the young child. Starchy foods are consumed uncooked (e.g., fruit or vegetable salad) or cooked (e.g., mashed potato), and in granule (insoluble) or gelatinized (soluble) forms. Various aspects of digestive enzymes in the young child are described, including pancreatic a-amylase deficiency and the existence of salivary a-amylase, milk a-amylase, blood a-amylase, and a-glucosidases. The young child can digest starchy foods and absorb dietary glucose. Among the various sources of starches, rice maltodextrin is most digestible because of its unique structural characteristics. Common sources of complementary starches are also described. This review would benefit the food industry in designing complementary foods (also known as beikost), and also health providers, such as pediatricians and dietitians in understanding starch digestion and the difference between granuley and gelatinized starch.

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“…Although pancreatic a-amylase is often considered the principal enzyme of starch digestion, SI and MGAM represent the control point for glucose generation. Their activities at the luminal-facing apical membrane of the enterocytes are relevant to glucose control (7). SI contains both a-1,4 and a-1,6 activities necessary to produce glucose from starch digestion, whereas MGAM essentially has only a-1,4 activity.…”

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confidence: 99%

Dietary starch breakdown product sensing mobilizes and apically activates α‐glucosidases in small intestinal enterocytes

et al. 2018

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Dietary starch is finally converted to glucose for absorption by the small intestine mucosal α-glucosidases (sucrase-isomaltase [SI] and maltase-glucoamylase), and control of this process has health implications. Here, the molecular mechanisms were analyzed associated with starch-triggered maturation and transport of SI. Biosynthetic pulse-chase in Caco-2 cells revealed that the high MW SI species (265 kDa) induced by maltose (an α-amylase starch digestion product) had a higher rate of early trafficking and maturation compared with a glucose-induced SI (245 kDa). The maltose-induced SI was found to have higher affinity to lipid rafts, which are associated with enhanced targeting to the apical membrane and higher activity. Accordingly, in situ maltose-hydrolyzing action was enhanced in the maltose-treated cells. Thus, starch digestion products at the luminal surface of small intestinal enterocytes are sensed and accelerate the intracellular processing of SI to enhance starch digestion capacity in the intestinal lumen.-Chegeni, M., Amiri, M., Nichols, B. L., Naim, H. Y., Hamaker, B. R. Dietary starch breakdown product sensing mobilizes and apically activates α-glucosidases in small intestinal enterocytes.

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Mucosal C‐terminal maltase‐glucoamylase hydrolyzes large size starch digestion products that may contribute to rapid postprandial glucose generation

Abstract: The findings suggest that partial inhibition of ctMGAM, such as by natural inhibitors found in foods, might be used to moderate the early stage of high glycemic response, as well as to extend digestion distally; thereby having relevance in regulating glucose delivery to the body.

Cited by 41 publications

References 45 publications

Rethinking the starch digestion hypothesis for AMY1 copy number variation in humans

Rethinking the starch digestion hypothesis for AMY1 copy number variation in humans

The digestion of complementary feeding starches in the young child

Dietary starch breakdown product sensing mobilizes and apically activates α‐glucosidases in small intestinal enterocytes

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