title: Investigating the mechanisms of amylolysis of starch granules by solution-state NMR.
abstract: Starch is a prominent component of the human diet and is hydrolyzed by α-amylase post-ingestion. Probing the mechanism of this process has proven challenging, due to the intrinsic heterogeneity of individual starch granules. By means of solution-state NMR, we demonstrate that flexible polysaccharide chains protruding from the solvent-exposed surfaces of waxy rice starch granules are highly mobile and that during hydrothermal treatment, when the granules swell, the number of flexible residues on the exposed surfaces increases by a factor of 15. Moreover, we show that these flexible chains are the primary substrates for α-amylase, being cleaved in the initial stages of hydrolysis. These findings allow us to conclude that the quantity of flexible α-glucan chains protruding from the granule surface will greatly influence the rate of energy acquisition from digestion of starch.
authors: †Department of Chemistry, University of Cambridge, Lensfield Road, Cambridge, CB2 1EW, United Kingdom.
authors: Andrew J
authors: AJ
authors: Baldwin
authors: §Biopolymers Group, Diabetes and Nutritional Sciences Division, King's College London, Franklin-Wilkins Building, 150 Stamford Street, London, SE1 9NH, United Kingdom.
authors: Danielle L
authors: DL
authors: Egan
authors: §Biopolymers Group, Diabetes and Nutritional Sciences Division, King's College London, Franklin-Wilkins Building, 150 Stamford Street, London, SE1 9NH, United Kingdom.
authors: Fredrick J
authors: FJ
authors: Warren
authors: †Department of Chemistry, University of Cambridge, Lensfield Road, Cambridge, CB2 1EW, United Kingdom.
authors: Paul D
authors: PD
authors: Barker
authors: †Department of Chemistry, University of Cambridge, Lensfield Road, Cambridge, CB2 1EW, United Kingdom.
authors: Christopher M
authors: CM
authors: Dobson
authors: §Biopolymers Group, Diabetes and Nutritional Sciences Division, King's College London, Franklin-Wilkins Building, 150 Stamford Street, London, SE1 9NH, United Kingdom.
authors: Peter J
authors: PJ
authors: Butterworth
authors: §Biopolymers Group, Diabetes and Nutritional Sciences Division, King's College London, Franklin-Wilkins Building, 150 Stamford Street, London, SE1 9NH, United Kingdom.
authors: Peter R
authors: PR
authors: Ellis
mesh_terms: D000687:Amylopectin / Q000737:chemistry; D006801:Humans; D006868:Hydrolysis; D007700:Kinetics; D009682:Magnetic Resonance Spectroscopy; D012275:Oryza; D012996:Solutions / Q000737:chemistry*; D013213:Starch / Q000737:chemistry*; D000516:alpha-Amylases / Q000737:chemistry*
chemical_list: D012996:Solutions; D013213:Starch; D000687:Amylopectin; D000516:alpha-Amylases