Isomaltase Explained

Ec Number:3.2.1.10
Oligo-1,6-glucosidase

Isomaltase is an enzyme that breaks the bonds linking saccharides, which cannot be broken by amylase or maltase. It digests polysaccharides at the alpha 1-6 linkages. Its substrate, alpha-limit dextrin, is a product of amylopectin digestion that retains its 1-6 linkage (its alpha 1-4 linkages having already been broken down by amylase). The product of the enzymatic digestion of alpha-limit dextrin by isomaltase is maltose.

Isomaltase helps amylase to digest alpha-limit dextrin to produce maltose. The human sucrase-isomaltase is a dual-function enzyme with two GH31 domains, one serving as the isomaltase, the other as a sucrose alpha-glucosidase.

Nomenclature

The systematic name of sucrase-isomaltase is oligosaccharide 6-alpha-glucohydrolase. This enzyme is also known as:

Mechanism

This enzyme catalyses the following chemical reaction

Hydrolysis of (1->6)-alpha-D-glucosidic linkages in some oligosaccharides produced from starch and glycogen by enzyme EC 3.2.1.1.Hydrolysis uses water to cleave chemical bonds. Sucrase-isomaltase’s mechanism results in a net retention of configuration at the anomeric center.[1]

Notes and References

  1. Sim L, Willemsma C, Mohan S, Naim HY, Pinto BM, Rose DR . Structural basis for substrate selectivity in human maltase-glucoamylase and sucrase-isomaltase N-terminal domains . The Journal of Biological Chemistry . 285 . 23 . 17763–70 . June 2010 . 20356844 . 2878540 . 10.1074/jbc.M109.078980 . free .