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Dietary Glucogenesis by Mucosal α‐Glucosidase is Influenced by the Internal Molecular Structure of Starch Hydrolysates
Author(s) -
Muniandy Anbuhkani,
Lin Amy
Publication year - 2015
Publication title -
the faseb journal
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.709
H-Index - 277
eISSN - 1530-6860
pISSN - 0892-6638
DOI - 10.1096/fasebj.29.1_supplement.596.8
Subject(s) - hydrolysate , dextrin , chemistry , starch , food science , hydrolysis , digestion (alchemy) , amylose , degree of polymerization , amylase , potato starch , biochemistry , polymerization , chromatography , enzyme , organic chemistry , polymer
Four small intestinal α‐glucosidases, N‐ and C‐terminal subunits of maltase‐glucoamylase (MGAM) and sucrase‐isomaltase (SI), releases glucose from starch molecules at the final stage of digestion in the small intestine. In our previous study, we hypothesized that the digestibility at α‐glucosidase level is determined by the internal molecular structure of starch hydrolysates. We later reported that the branch pattern of starch internal molecules influences the digestion. The objective of this study is to further test the hypothesis that the branch amount and the distance between branches influence the rate and extent of glucose release from α‐amylase hydrolysate. Two starches [waxy (wx) maize and potato] with different internal structure were hydrolyzed by pancreatic α‐amylase. The hydrolysate consists of linear glucans and branched dextrin (α‐limit dextrin,α‐LD), and they were separated by size‐exclusion chromatography. α‐LD was digested by Ct‐MGAM in vitro, and the rate and extent of glucose release were examined. Both wx maize and potato hydrolysates consist of 30‐35% of α‐LD, and the molecular size of their α‐LD was DP (average degree of polymerization)13 and 17, respectively. The amount of released glucose from wx maize and potato α‐LD was 30 and 40 mg ( p <0.05), and the rate of glucose release as represented by the catalytic efficiency was 0.13 and 0.28, respectively. In conclusion, α‐LD with longer distance between branches and loose branched structure (potato in this study) generated higher glucose amount at higher rate by Ct‐MGAM. In the future, starches with different type of internal structure needs to be further examined. This project was sponsored by Univ. of Idaho and Whistler Center for Carbohydrate Research at Purdue Univ.