Unexpected high digestion rate of cooked starch by the Ct-Maltase-Glucoamylase small intenstine mucosal a-Glucosidase subunit

Abstract

For starch digestion to glucose, two luminal a-amylases and four gut mucosal a-glucosidase subunits are employed. The aim of this research was to investigate, for the first time, direct digestion capability of individual mucosal a-glucosidases on cooked (gelatinized) starch. Gelatinized normal maize starch was digested with N- and C-terminal subunits of recombinant mammalian maltase-glucoamylase (MGAM) and sucrase-isomaltase (SI) of varying amounts and digestion periods. Without the aid of a-amylase, Ct-MGAM demonstrated an unexpected rapid and high digestion degree near 80%, while other subunits showed 20 to 30% digestion. These findings suggest that Ct-MGAM assists a-amylase in digesting starch molecules and potentially may compensate for developmental or pathological amylase deficiencies.