glycogen debranching protein GlgX.

Pullulanase/glycogen debranching enzyme [Carbohydrate transport and metabolism].

bifunctional glycogen debranching protein GlgX/4-alpha-glucanotransferase.

Alpha amylase catalytic domain found in glycogen debranching enzymes. Debranching enzymes facilitate the breakdown of glycogen through glucosyltransferase and glucosidase activity. These activities are performed by a single enzyme in mammals, yeast, and some bacteria, but by two distinct enzymes in Escherichia coli and other bacteria. Debranching enzymes perform two activities: 4-alpha-D-glucanotransferase (EC 2.4.1.25) and amylo-1,6-glucosidase (EC 3.2.1.33). 4-alpha-D-glucanotransferase catalyzes the endohydrolysis of 1,6-alpha-D-glucoside linkages at points of branching in chains of 1,4-linked alpha-D-glucose residues. Amylo-alpha-1,6-glucosidase catalyzes the endohydrolysis of 1,6-alpha-D-glucoside linkages at points of branching in chains of 1,4-linked alpha-D-glucose residues. In Escherichia coli, GlgX is the debranching enzyme and malQ is the 4-alpha-glucanotransferase. TreX, an archaeal glycogen-debranching enzyme has dual activities like mammals and yeast, but is structurally similar to GlgX. TreX exists in two oligomeric states, a dimer and tetramer. Isoamylase (EC 3.2.1.68) is one of the starch-debranching enzymes that catalyzes the hydrolysis of alpha-1,6-glucosidic linkages specific in alpha-glucans such as amylopectin or glycogen and their beta-limit dextrins. The Alpha-amylase family comprises the largest family of glycoside hydrolases (GH), with the majority of enzymes acting on starch, glycogen, and related oligo- and polysaccharides. These proteins catalyze the transformation of alpha-1,4 and alpha-1,6 glucosidic linkages with retention of the anomeric center. The protein is described as having 3 domains: A, B, C. A is a (beta/alpha) 8-barrel; B is a loop between the beta 3 strand and alpha 3 helix of A; C is the C-terminal extension characterized by a Greek key. The majority of the enzymes have an active site cleft found between domains A and B where a triad of catalytic residues (Asp, Glu and Asp) performs catalysis. Other members of this family have lost the catalytic activity as in the case of the human 4F2hc, or only have 2 residues that serve as the catalytic nucleophile and the acid/base, such as Thermus A4 beta-galactosidase with 2 Glu residues (GH42) and human alpha-galactosidase with 2 Asp residues (GH31). The family members are quite extensive and include: alpha amylase, maltosyltransferase, cyclodextrin glycotransferase, maltogenic amylase, neopullulanase, isoamylase, 1,4-alpha-D-glucan maltotetrahydrolase, 4-alpha-glucotransferase, oligo-1,6-glucosidase, amylosucrase, sucrose phosphorylase, and amylomaltase.

N-terminal Early set domain associated with the catalytic domain of Glycogen debranching enzyme and bacterial isoamylase (also called glycogen 6-glucanohydrolase). E or "early" set domains are associated with the catalytic domain of the glycogen debranching enzyme at the N-terminal end. Glycogen debranching enzymes have both 4-alpha-glucanotransferase and amylo-1,6-glucosidase activities. As a transferase, it transfers a segment of the 1,4-alpha-D-glucan to a new 4-position in an acceptor, which may be glucose or another 1,4-alpha-D-glucan. As a glucosidase, it catalyzes the endohydrolysis of 1,6-alpha-D-glucoside linkages at points of branching in chains of 1,4-linked alpha-D-glucose residues. Bacterial isoamylases are also included in this subfamily. Isoamylase is one of the starch-debranching enzymes that catalyze the hydrolysis of alpha-1,6-glucosidic linkages specific in alpha-glucans such as amylopectin or glycogen. Isoamylase contains a bound calcium ion, but this is not in the same position as the conserved calcium ion that has been reported in other alpha-amylase family enzymes. The N-terminal domain of glycogen debranching enzyme may be related to the immunoglobulin and/or fibronectin type III superfamilies. These domains are associated with different types of catalytic domains at either the N-terminal or C-terminal end and may be involved in homodimeric/tetrameric/dodecameric interactions. Members of this family include members of the alpha amylase family, sialidase, galactose oxidase, cellulase, cellulose, hyaluronate lyase, chitobiase, and chitinase, among others.

Crystalstructure of Glycogen Debranching enzyme TreX from Sulfolobus solfataricus [Saccharolobus solfataricus],2VNC_B Crystal structure of Glycogen Debranching enzyme TreX from Sulfolobus solfataricus [Saccharolobus solfataricus],2VR5_A Crystal structure of Trex from Sulfolobus Solfataricus in complex with acarbose intermediate and glucose [Saccharolobus solfataricus],2VR5_B Crystal structure of Trex from Sulfolobus Solfataricus in complex with acarbose intermediate and glucose [Saccharolobus solfataricus],2VUY_A Crystal structure of Glycogen Debranching exzyme TreX from Sulfolobus solfatarius [Saccharolobus solfataricus],2VUY_B Crystal structure of Glycogen Debranching exzyme TreX from Sulfolobus solfatarius [Saccharolobus solfataricus],7EAV_A Chain A, Glycogen debranching enzyme [Saccharolobus solfataricus],7EAV_B Chain B, Glycogen debranching enzyme [Saccharolobus solfataricus]

Crystalstructure of Glycogen Debranching Enzyme GlgX from Escherichia coli K-12 [Escherichia coli K-12]

CrystalStructure of Chlamydomonas reinhardtii Isoamylase 1 (ISA1) [Chlamydomonas reinhardtii],4J7R_B Crystal Structure of Chlamydomonas reinhardtii Isoamylase 1 (ISA1) [Chlamydomonas reinhardtii],4OKD_A Crystal Structure of Chlamydomonas reinhardtii Isoamylase 1 (ISA1) in complex with maltoheptaose [Chlamydomonas reinhardtii],4OKD_B Crystal Structure of Chlamydomonas reinhardtii Isoamylase 1 (ISA1) in complex with maltoheptaose [Chlamydomonas reinhardtii]

StructureOf Pseudomonas Isoamylase [Pseudomonas amyloderamosa]

TheX-ray Crystallographic Structure of Branching Enzyme from Rhodothermus obamensis STB05 [Rhodothermus marinus]

Glycogen debranching enzyme OS=Shigella boydii serotype 4 (strain Sb227) OX=300268 GN=glgX PE=3 SV=1

Glycogen debranching enzyme OS=Escherichia coli O81 (strain ED1a) OX=585397 GN=glgX PE=3 SV=1

Glycogen debranching enzyme OS=Shigella dysenteriae serotype 1 (strain Sd197) OX=300267 GN=glgX PE=3 SV=1

Glycogen debranching enzyme OS=Escherichia coli O17:K52:H18 (strain UMN026 / ExPEC) OX=585056 GN=glgX PE=3 SV=1

Glycogen debranching enzyme OS=Escherichia coli O127:H6 (strain E2348/69 / EPEC) OX=574521 GN=glgX PE=3 SV=1