Isomaltase
Enzyme
From Wikipedia, the free encyclopedia
Isomaltase (EC 3.2.1.10) 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.
| Oligo-1,6-glucosidase | |||||||||
|---|---|---|---|---|---|---|---|---|---|
| Identifiers | |||||||||
| EC no. | 3.2.1.10 | ||||||||
| Databases | |||||||||
| IntEnz | IntEnz view | ||||||||
| BRENDA | BRENDA entry | ||||||||
| ExPASy | NiceZyme view | ||||||||
| KEGG | KEGG entry | ||||||||
| MetaCyc | metabolic pathway | ||||||||
| PRIAM | profile | ||||||||
| PDB structures | RCSB PDB PDBe PDBsum | ||||||||
| |||||||||
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:
- Sucrase-alpha-dextrinase
- oligo-1,6-glucosidase,
- limit dextrin,
- so maltase,
- exo-oligo-1,6-glucosidase,
- dextrin 6alpha-glucanohydrolase,
- alpha-limit dextrin,
- dextrin 6-glucanohydrolase, and
- oligosaccharide alpha-1,6-glucohydrolase.
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]
External links
- Isomaltase at the U.S. National Library of Medicine Medical Subject Headings (MeSH)
