| cd02856 | E_set_GDE_Isoamylase_N | 2.0e-14 | 117 | 216 | 104 | +
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. |
| cd02853 | E_set_MTHase_like_N | 2.0e-15 | 134 | 199 | 66 | +
N-terminal Early set domain associated with the catalytic domain of Maltooligosyl trehalose trehalohydrolase (also called Glycosyltrehalose trehalohydrolase) and similar proteins. E or "early" set domains are associated with the catalytic domain of Maltooligosyl trehalose trehalohydrolase (MTHase) and similar proteins at the N-terminal end. This subfamily also includes bacterial alpha amylases and 1,4-alpha-glucan branching enzymes which are highly similar to MTHase. Maltooligosyl trehalose synthase (MTSase) and MTHase work together to produce trehalose. MTSase is responsible for converting the alpha-1,4-glucosidic linkage to an alpha,alpha-1,1-glucosidic linkage at the reducing end of the maltooligosaccharide through an intramolecular transglucosylation reaction, while MTHase hydrolyzes the penultimate alpha-1,4 linkage of the reducing end, resulting in the release of trehalose. The N-terminal domain of MTHase 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. |
| cd05467 | CBM20 | 1.0e-29 | 124 | 216 | 96 | +
The family 20 carbohydrate-binding module (CBM20), also known as the starch-binding domain, is found in a large number of starch degrading enzymes including alpha-amylase, beta-amylase, glucoamylase, and CGTase (cyclodextrin glucanotransferase). CBM20 is also present in proteins that have a regulatory role in starch metabolism in plants (e.g. alpha-amylase) or glycogen metabolism in mammals (e.g. laforin). CBM20 folds as an antiparallel beta-barrel structure with two starch binding sites. These two sites are thought to differ functionally with site 1 acting as the initial starch recognition site and site 2 involved in the specific recognition of appropriate regions of starch. |
