Alpha amylase catalytic domain found in the Glycogen branching enzyme (also called 1,4-alpha-glucan branching enzyme). The glycogen branching enzyme catalyzes the third step of glycogen biosynthesis by the cleavage of an alpha-(1,4)-glucosidic linkage and the formation a new alpha-(1,6)-branch by subsequent transfer of cleaved oligosaccharide. They are part of a group called branching enzymes which catalyze the formation of alpha-1,6 branch points in either glycogen or starch. This group includes proteins from bacteria, eukaryotes, and archaea. 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.

1,4-alpha-glucan branching protein GlgB.

1,4-alpha-glucan branching enzyme [Carbohydrate transport and metabolism].

1,4-alpha-glucan branching protein GlgB.

glycogen branching enzyme; Provisional

ChainA, 1,4-alpha-glucan branching enzyme GlgB [Crocosphaera subtropica ATCC 51142]

Crystalstructure of branching enzyme L541A/W655A mutant from Cyanothece sp. ATCC 51142 [Crocosphaera subtropica ATCC 51142]

Crystalstructure of branching enzyme Y500A mutant from Cyanothece sp. ATCC 51142 [Crocosphaera subtropica ATCC 51142]

Crystalstructure of branching enzyme Y500A/D501A mutant from Cyanothece sp. ATCC 51142 in complex with maltoheptaose [Crocosphaera subtropica ATCC 51142],5GR6_A Crystal structure of branching enzyme Y500A/D501A double mutant from Cyanothece sp. ATCC 51142 [Crocosphaera subtropica ATCC 51142]

Crystalstructure of branching enzyme D501A mutant from Cyanothece sp. ATCC 51142 [Crocosphaera subtropica ATCC 51142]

1,4-alpha-glucan branching enzyme GlgB OS=Bacillus cytotoxicus (strain DSM 22905 / CIP 110041 / 391-98 / NVH 391-98) OX=315749 GN=glgB PE=3 SV=1

1,4-alpha-glucan branching enzyme GlgB OS=Bacillus subtilis (strain 168) OX=224308 GN=glgB PE=2 SV=1

1,4-alpha-glucan branching enzyme GlgB 2 OS=Clostridium perfringens (strain SM101 / Type A) OX=289380 GN=glgB2 PE=3 SV=1

1,4-alpha-glucan branching enzyme GlgB OS=Bacillus cereus (strain ZK / E33L) OX=288681 GN=glgB PE=3 SV=1

1,4-alpha-glucan branching enzyme GlgB OS=Clostridium perfringens (strain ATCC 13124 / DSM 756 / JCM 1290 / NCIMB 6125 / NCTC 8237 / Type A) OX=195103 GN=glgB PE=3 SV=1