Alpha amylase catalytic domain found in cyclomaltodextrinases and related proteins. Cyclomaltodextrinase (CDase; EC3.2.1.54), neopullulanase (NPase; EC 3.2.1.135), and maltogenic amylase (MA; EC 3.2.1.133) catalyze the hydrolysis of alpha-(1,4) glycosidic linkages on a number of substrates including cyclomaltodextrins (CDs), pullulan, and starch. These enzymes hydrolyze CDs and starch to maltose and pullulan to panose by cleavage of alpha-1,4 glycosidic bonds whereas alpha-amylases essentially lack activity on CDs and pullulan. They also catalyze transglycosylation of oligosaccharides to the C3-, C4- or C6-hydroxyl groups of various acceptor sugar molecules. Since these proteins are nearly indistinguishable from each other, they are referred to as cyclomaltodextrinases (CMDs). 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.

4-alpha-glucanotransferase; Provisional

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

disproportionating enzyme

4-alpha-glucanotransferase. These enzymes EC:2.4.1.25 transfer a segment of a (1,4)-alpha-D-glucan to a new 4-position in an acceptor, which may be glucose or (1,4)-alpha-D-glucan.

CrystalStructure Of Amylomaltase From Thermus Aquaticus, A Glycosyltransferase Catalysing The Production Of Large Cyclic Glucans [Thermus aquaticus],1ESW_A X-Ray Structure Of Acarbose Bound To Amylomaltase From Thermus Aquaticus. Implications For The Synthesis Of Large Cyclic Glucans [Thermus aquaticus]

StructureOf The Amylomaltase From Thermus Thermophilus Hb8 In Space Group P21212 [Thermus thermophilus],1FP9_A Structure Of Amylomaltase From Thermus Thermophilus Hb8 In Space Group C2 [Thermus thermophilus]

Structureof a covalent intermediate in Thermus thermophilus amylomaltase [Thermus thermophilus],2OWW_A Covalent intermediate in amylomaltase in complex with the acceptor analog 4-deoxyglucose [Thermus thermophilus],2OWX_A THERMUS THERMOPHILUS AMYLOMALTASE AT pH 5.6 [Thermus thermophilus]

Crystalstructure of Thermus aquaticus amylomaltase (GH77) in complex with a 34-meric cycloamylose [Thermus aquaticus]

glycosidehydrolase family 77 4-alpha-glucanotransferase from thermus brockianus [Thermus brockianus]

4-alpha-glucanotransferase OS=Streptococcus pneumoniae (strain ATCC BAA-255 / R6) OX=171101 GN=malQ PE=3 SV=1

4-alpha-glucanotransferase OS=Streptococcus pneumoniae serotype 4 (strain ATCC BAA-334 / TIGR4) OX=170187 GN=malQ PE=3 SV=1

4-alpha-glucanotransferase OS=Synechocystis sp. (strain PCC 6803 / Kazusa) OX=1111708 GN=malQ PE=3 SV=1

4-alpha-glucanotransferase OS=Thermus thermophilus OX=274 GN=malQ PE=1 SV=1

4-alpha-glucanotransferase OS=Aquifex aeolicus (strain VF5) OX=224324 GN=malQ PE=1 SV=1