| 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 (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.
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.
The systematic name of sucrase-isomaltase is oligosaccharide 6-alpha-glucohydrolase. This enzyme is also known as:
This enzyme catalyses the following chemical reaction
Hydrolysis uses water to cleave chemical bonds. Sucrase-isomaltase’s mechanism results in a net retention of configuration at the anomeric center. [1]
A disaccharide is the sugar formed when two monosaccharides are joined by glycosidic linkage. Like monosaccharides, disaccharides are simple sugars soluble in water. Three common examples are sucrose, lactose, and maltose.
Hydrolysis is any chemical reaction in which a molecule of water breaks one or more chemical bonds. The term is used broadly for substitution, elimination, and solvation reactions in which water is the nucleophile.
An amylase is an enzyme that catalyses the hydrolysis of starch into sugars. Amylase is present in the saliva of humans and some other mammals, where it begins the chemical process of digestion. Foods that contain large amounts of starch but little sugar, such as rice and potatoes, may acquire a slightly sweet taste as they are chewed because amylase degrades some of their starch into sugar. The pancreas and salivary gland make amylase to hydrolyse dietary starch into disaccharides and trisaccharides which are converted by other enzymes to glucose to supply the body with energy. Plants and some bacteria also produce amylase. Specific amylase proteins are designated by different Greek letters. All amylases are glycoside hydrolases and act on α-1,4-glycosidic bonds.
Maltose, also known as maltobiose or malt sugar, is a disaccharide formed from two units of glucose joined with an α(1→4) bond. In the isomer isomaltose, the two glucose molecules are joined with an α(1→6) bond. Maltose is the two-unit member of the amylose homologous series, the key structural motif of starch. When alpha-amylase breaks down starch, it removes two glucose units at a time, producing maltose. An example of this reaction is found in germinating seeds, which is why it was named after malt. Unlike sucrose, it is a reducing sugar.
Maltase is one type of alpha-glucosidase enzymes located in the brush border of the small intestine. This enzyme catalyzes the hydrolysis of disaccharide maltose into two simple sugars of glucose. Maltase is found in plants, bacteria, yeast, humans, and other vertebrates. It is thought to be synthesized by cells of the mucous membrane lining the intestinal wall.
Dextrins are a group of low-molecular-weight carbohydrates produced by the hydrolysis of starch or glycogen. Dextrins are mixtures of polymers of D-glucose units linked by α-(1→4) or α-(1→6) glycosidic bonds.
Pullulanase is a specific kind of glucanase, an amylolytic exoenzyme, that degrades pullulan. It is produced as an extracellular, cell surface-anchored lipoprotein by Gram-negative bacteria of the genus Klebsiella. Type I pullulanases specifically attack α-1,6 linkages, while type II pullulanases are also able to hydrolyse α-1,4 linkages. It is also produced by some other bacteria and archaea. Pullulanase is used as a processing aid in grain processing biotechnology.
Carbohydrase is the name of a set of enzymes that catalyze 5 types of reactions, turning carbohydrates into simple sugars, from the large family of glycosidases.
Beta-amylase is an enzyme with the systematic name 4-alpha-D-glucan maltohydrolase. This enzyme catalyses the following chemical reaction:
Sucrase-isomaltase (SI) is a glucosidase enzyme located on the brush border of the small intestine. It is a dual-function enzyme with two GH31 domains, one serving as the isomaltase, the other as a sucrose alpha-glucosidase. It has preferential expression in the apical membranes of enterocytes. The enzyme’s purpose is to digest dietary carbohydrates such as starch, sucrose and isomaltose. By further processing the broken-down products, energy in the form of ATP can be generated.
Alpha-amylase(α-amylase) is an enzyme EC 3.2.1.1 that hydrolyses alpha bonds of large, alpha-linked polysaccharides, such as starch and glycogen, yielding shorter chains thereof, dextrins, and maltose. It is the major form of amylase found in humans and other mammals. It is also present in seeds containing starch as a food reserve, and is secreted by many fungi. It is a member of glycoside hydrolase family 13.
Glucan 1,4-alpha-glucosidase is an enzyme located on the brush border of the small intestine with systematic name 4-alpha-D-glucan glucohydrolase. This enzyme catalyses the following chemical reaction
Maltase-glucoamylase, intestinal is an enzyme that in humans is encoded by the MGAM gene.
Limit dextrinase is an enzyme with systematic name dextrin 6-alpha-glucanohydrolase. This enzyme catalyses the hydrolysis of (1->6)-alpha-D-glucosidic linkages in alpha- and beta-limits dextrins of amylopectin and glycogen, in amylopectin and pullulan.
Amylo-alpha-1,6-glucosidase is an enzyme with systematic name glycogen phosphorylase-limit dextrin 6-alpha-glucohydrolase. This enzyme catalyses the following chemical reaction
Sucrose alpha-glucosidase is an enzyme with systematic name sucrose-alpha-D-glucohydrolase. This enzyme catalyses the following chemical reaction
Glucan 1,3-beta-glucosidase is an enzyme with systematic name 3-beta-D-glucan glucohydrolase. This enzyme catalyses the following chemical reaction
Glucan 1,6-alpha-glucosidase is an enzyme with systematic name glucan 6-alpha-D-glucohydrolase. This enzyme catalyses the following chemical reaction:
Branched-dextran exo-1,2-alpha-glucosidase is an enzyme with systematic name (1->2)-alpha-D-glucosyl-branched-dextran 2-glucohydrolase. This enzyme catalyses the following chemical reaction
Neopullulanase is an enzyme of the alpha-amylase family with systematic name pullulan 4-D-glucanohydrolase (panose-forming). This enzyme principally catalyses the following chemical reaction by cleaving pullulan's alpha-1,4-glucosidic bonds:
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