Sucrase-Isomaltase

• OMIM: 609845
• UniProt: P14410

Sucrase -isomaltase (Gen: SI ) is called the enzyme that catalyzes the hydrolytic cleavage of limit dextrins, maltotriose, maltose, isomaltose, sucrose, and other complex sugars. This reaction step is essential in the digestion of carbohydrates. The enzyme is found in all vertebrates and is produced in humans in the small intestine and to a small extent in the colon to the surface of the microvilli. There is associated with the cell wall myosin 1A. Mutations in the SI gene can sucrase - Isomaltasemangel and thus cause sucrose intolerance.

Catalyzed reaction

As an example of the separation of (1 → 6 )-alpha- D- glucosidic linkages:

H2O ⇒ 2

Isomaltose is cleaved into two glucose molecules.

Regulation

The activation of the SI gene is associated with changes in modifications of the histone H3 and binding of the transcription factor, Cdx -2 to the promoter region of the gene. These conditions include the result of a diet high in carbohydrate / fat ratio.

In the inhibition of gene expression by HNF- 1alpha glucose is involved.