TY - JOUR

T1 - Interfacial enzyme kinetics reveals degradation mechanisms behind resistant starch

AU - Tian, Yu

AU - Wang, Yu

AU - Liu, Xingxun

AU - Herburger, Klaus

AU - Westh, Peter

AU - Møller, Marie S.

AU - Svensson, Birte

AU - Zhong, Yuyue

AU - Blennow, Andreas

N1 - Publisher Copyright: © 2023 Elsevier Ltd

PY - 2023

Y1 - 2023

N2 - The digestive resistance of so-called resistant starch (RS) provides an important nutritional principle. However, as yet the mechanisms underlying digestive resistance of the granular starches are not well described. We address this problem by employing a novel enzyme kinetics approach, which in contrast to conventional enzyme kinetics takes the interfacial nature of the enzyme reaction into account. Structurally different starch granules with different amylose contents were modified by the hydrolytic enzyme glucoamylase (GA). Kinetic-, adsorbtion-, imaging-, particle size-, and spectroscopic data combinedly revealed important origins of hydrolytic resistance of high-amylose starch. Our data demonstrate that amylose restricted the enzymatic catalysis efficiency on starch granules chiefly by providing less hydrolytic effective attack sites for the enzyme at granular surface. Specifically, the total binding sites (adsΓmax) (20.9 nmol/g) on starch with 0% amylose content (AC) were almost all effective attack sites (kinΓmax) (20.2 nmol/g). At 26% AC, the binding sites on the granules decreased to 13.9 nmol/g, and attack sites decreased to 7.4%. At 72% AC, the binding sites were only slightly reduced to 11.2 nmol/g, however, the attack sites were remarkably decreased to 2.6 nmol/g. Beyond the initial catalytic events, i.e., for further degraded granules, the binding and catalysis efficiency differed notably for the three starch types. At 0% AC, both binding and attack increased demonstrating increased hydrolytic susceptibility of the granules. At 26% AC only binding increased, while attack was unchanged. Interestingly, at 72% AC, binding increased, while attack deceased notably with hydrolysis time, demonstrating decreased efficiency of interfacial catalysis during the hydrolysis process.

AB - The digestive resistance of so-called resistant starch (RS) provides an important nutritional principle. However, as yet the mechanisms underlying digestive resistance of the granular starches are not well described. We address this problem by employing a novel enzyme kinetics approach, which in contrast to conventional enzyme kinetics takes the interfacial nature of the enzyme reaction into account. Structurally different starch granules with different amylose contents were modified by the hydrolytic enzyme glucoamylase (GA). Kinetic-, adsorbtion-, imaging-, particle size-, and spectroscopic data combinedly revealed important origins of hydrolytic resistance of high-amylose starch. Our data demonstrate that amylose restricted the enzymatic catalysis efficiency on starch granules chiefly by providing less hydrolytic effective attack sites for the enzyme at granular surface. Specifically, the total binding sites (adsΓmax) (20.9 nmol/g) on starch with 0% amylose content (AC) were almost all effective attack sites (kinΓmax) (20.2 nmol/g). At 26% AC, the binding sites on the granules decreased to 13.9 nmol/g, and attack sites decreased to 7.4%. At 72% AC, the binding sites were only slightly reduced to 11.2 nmol/g, however, the attack sites were remarkably decreased to 2.6 nmol/g. Beyond the initial catalytic events, i.e., for further degraded granules, the binding and catalysis efficiency differed notably for the three starch types. At 0% AC, both binding and attack increased demonstrating increased hydrolytic susceptibility of the granules. At 26% AC only binding increased, while attack was unchanged. Interestingly, at 72% AC, binding increased, while attack deceased notably with hydrolysis time, demonstrating decreased efficiency of interfacial catalysis during the hydrolysis process.

KW - Digestion

KW - Enzymic kinetic

KW - Interfacial catalysis

KW - Starch granule

U2 - 10.1016/j.foodhyd.2023.108621

DO - 10.1016/j.foodhyd.2023.108621

M3 - Journal article

AN - SCOPUS:85150055209

VL - 140

JO - Food Hydrocolloids

JF - Food Hydrocolloids

SN - 0268-005X

M1 - 108621

ER -