Sucrase-isomaltase, intestinal (SI)

Sucrase-isomaltase, intestinal (SI), is a bifunctional enzyme located in the brush border membrane of enterocytes in the small intestine[1][3][6]. It consists of two subunits, sucrase and isomaltase, both members of the glycoside hydrolase family 31 (GH31), which are responsible for the final step in the digestion of dietary carbohydrates such as sucrose, isomaltose, and maltose into absorbable monosaccharides[1][2][4]. SI is essential for normal carbohydrate absorption and energy production. Mutations in the SI gene can cause congenital sucrase-isomaltase deficiency, leading to malabsorption and gastrointestinal symptoms[3][5]. SI activity can be inhibited by drugs such as acarbose and miglitol, which are used to slow glucose absorption in diabetes management. Interaction with another enzyme, maltase-glucoamylase, influences carbohydrate digestion efficiency and disease phenotypes in GI syndromes[5][1].

Other names

Sucrase-isomaltaseSIsucrase alpha-glucosidaseisomaltase (component of the complex)intestinal sucrasedisaccharidase

Alpha-glucosidase inhibition (inhibitors reduce enzymatic hydrolysis of disaccharides, slowing glucose absorption)