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.

maltodextrin glucosidase; Provisional

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

Glycosidase [Carbohydrate transport and metabolism].

Alpha amylase, catalytic domain. Alpha amylase is classified as family 13 of the glycosyl hydrolases. The structure is an 8 stranded alpha/beta barrel containing the active site, interrupted by a ~70 a.a. calcium-binding domain protruding between beta strand 3 and alpha helix 3, and a carboxyl-terminal Greek key beta-barrel domain.

CrystalStructure of Ttha1563 from Thermus thermophilus HB8 [Thermus thermophilus HB8],2Z1K_B Crystal Structure of Ttha1563 from Thermus thermophilus HB8 [Thermus thermophilus HB8],2Z1K_C Crystal Structure of Ttha1563 from Thermus thermophilus HB8 [Thermus thermophilus HB8],2Z1K_D Crystal Structure of Ttha1563 from Thermus thermophilus HB8 [Thermus thermophilus HB8]

CrystalStructure Of A Maltogenic Amylase [Thermus sp. IM6501],1SMA_B Crystal Structure Of A Maltogenic Amylase [Thermus sp. IM6501]

ChainA, Pullulanase type II, GH13 family [Thermococcus kodakarensis]

Thermusmaltogenic amylase in complex with beta-CD [Thermus sp.],1GVI_B Thermus maltogenic amylase in complex with beta-CD [Thermus sp.]

Crystalstructure of Bacillus stearothermophilus neopullulanase [Geobacillus stearothermophilus],1J0H_B Crystal structure of Bacillus stearothermophilus neopullulanase [Geobacillus stearothermophilus],1J0I_A Crystal structure of neopullulanase complex with panose [Geobacillus stearothermophilus],1J0I_B Crystal structure of neopullulanase complex with panose [Geobacillus stearothermophilus]

Amylopullulanase OS=Thermoanaerobacter pseudethanolicus (strain ATCC 33223 / 39E) OX=340099 GN=apu PE=1 SV=2

Amylopullulanase OS=Thermoanaerobacterium saccharolyticum OX=28896 GN=apu PE=3 SV=2

Amylopullulanase OS=Thermoanaerobacter thermohydrosulfuricus OX=1516 GN=apu PE=1 SV=1

Amylopullulanase OS=Thermoanaerobacterium thermosulfurigenes OX=33950 GN=amyB PE=3 SV=2

Cyclomaltodextrinase OS=Geobacillus thermopakistaniensis (strain MAS1) OX=1408282 GN=T260_08735 PE=1 SV=1