Small intestine mucosal alpha-glucosidase: A missing feature of in vitro starch digestibility

Abstract

The quality of starch digestion related to the rate and extent of glucose release is associated with high glycemia-related health issues such as diabetes and other metabolic syndromes. In humans, two types of digestive enzymes, alpha-amylase and mucosal alpha-glucosidase, are involved in breaking down starch molecules to absorbable glucose. To evaluate starch digestion in vitro, which is an affordable and efficient way to examine the nutritional quality of starchy foods during the process of product development, it is common to use a combination of porcine alpha-amylase and fungal glucoamylase to determine the digestibility. Fungal glucoamylase converts alpha-amylase hydrolyzates to glucose and directly hydrolyzes starch molecules to glucose. Although its functions look similar to human small intestinal alpha-glucosidase, its hydrolytic mechanism and influence in physiologic responses are quite different. In this article, we review the structure and properties of the small intestine alpha-glucosidases, including their protein structure, hydrolytic activity, digestion capability, distribution in the small intestine, and the dietary influence in their activity and synthesis. (C) 2015 Published by Elsevier Ltd.