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Structural and enzyme kinetic studies of retrograded starch: Inhibition of ?-amylase and consequences for intestinal digestion of starch.

ABSTRACT: Retrograded starch is known to be resistant to digestion. We used enzyme kinetic experiments to examine how retrogradation of starch affects amylolysis catalysed by porcine pancreatic amylase. Parallel studies employing differential scanning calorimetry, infra red spectroscopy, X-ray diffraction and NMR spectroscopy were performed to monitor changes in supramolecular structure of gelatinised starch as it becomes retrograded. The total digestible starch and the catalytic efficiency of amylase were both decreased with increasing evidence of retrogradation. A purified sample of retrograded high amylose starch inhibited amylase directly. These new findings demonstrate that amylase binds to retrograded starch. Therefore consumption of retrograded starch may not only be beneficial to health through depletion of total digestible starch, and therefore the metabolisable energy, but may also slow the rate of intestinal digestion through direct inhibition of ?-amylase. Such physiological effects have important implications for the prevention and management of type 2 diabetes and cardiovascular disease.

SUBMITTER: Patel H

PROVIDER: S-EPMC5374268 | biostudies-literature | 2017 May

REPOSITORIES: biostudies-literature

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Structural and enzyme kinetic studies of retrograded starch: Inhibition of α-amylase and consequences for intestinal digestion of starch.

Patel Hamung H Royall Paul G PG Gaisford Simon S Williams Gareth R GR Edwards Cathrina H CH Warren Frederick J FJ Flanagan Bernadine M BM Ellis Peter R PR Butterworth Peter J PJ

Carbohydrate polymers 20170116

Retrograded starch is known to be resistant to digestion. We used enzyme kinetic experiments to examine how retrogradation of starch affects amylolysis catalysed by porcine pancreatic amylase. Parallel studies employing differential scanning calorimetry, infra red spectroscopy, X-ray diffraction and NMR spectroscopy were performed to monitor changes in supramolecular structure of gelatinised starch as it becomes retrograded. The total digestible starch and the catalytic efficiency of amylase wer ...[more]

PMID: 28325312

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Project description:Starch digestion in the human body is typically viewed in a sequential manner beginning with ?-amylase and followed by ?-glucosidase to produce glucose. This report indicates that the two enzyme types can act synergistically to digest granular starch structure. The aim of this study was to investigate how the mucosal ?-glucosidases act with ?-amylase to digest granular starch. Two types of enzyme extracts, pancreatic and intestinal extracts, were applied. The pancreatic extract containing predominantly ?-amylase, and intestinal extract containing a combination of ?-amylase and mucosal ?-glucosidase activities, were applied to three granular maize starches with different amylose contents in an in vitro system. Relative glucogenesis, released maltooligosaccharide amounts, and structural changes of degraded residues were examined. Pancreatic extract-treated starches showed a hydrolysis limit over the 12 h incubation period with residues having a higher gelatinization temperature than the native starch. ?-Amylase combined with the mucosal ?-glucosidases in the intestinal extract showed higher glucogenesis as expected, but also higher maltooligosaccharide amounts indicating an overall greater degree of granular starch breakdown. Starch residues after intestinal extract digestion showed more starch fragmentation, higher gelatinization temperature, higher crystallinity (without any change in polymorph), and an increase of intermediate-sized or small-sized fractions of starch molecules, but did not show preferential hydrolysis of either amylose or amylopectin. Direct digestion of granular starch by mammalian recombinant mucosal ?-glucosidases was observed which shows that these enzymes may work either independently or together with ?-amylase to digest starch. Thus, mucosal ?-glucosidases can have a synergistic effect with ?-amylase on granular starch digestion, consistent with a role in overall starch digestion beyond their primary glucogenesis function.

Dataset Information

Structural and enzyme kinetic studies of retrograded starch: Inhibition of ?-amylase and consequences for intestinal digestion of starch.

Publications

Structural and enzyme kinetic studies of retrograded starch: Inhibition of α-amylase and consequences for intestinal digestion of starch.

Similar Datasets

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