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.

This CD includes PGM2 (phosphoglucomutase 2) and PGM2L1 (phosphoglucomutase 2-like 1). The mammalian PGM2 is thought to be a phosphopentomutase that catalyzes the conversion of the nucleoside breakdown products, ribose-1-phosphate and deoxyribose-1-phosphate to the corresponding 5-phosphopentoses. PGM2L1 is thought to catalyze the 1,3-bisphosphoglycerate-dependent synthesis of glucose 1,6-bisphosphate and other aldose-bisphosphates that serve as cofactors for several sugar phosphomutases and possibly also as regulators of glycolytic enzymes. PGM2 and PGM2L1 belong to the alpha-D-phosphohexomutase superfamily which includes several related enzymes that catalyze a reversible intramolecular phosphoryl transfer on their sugar substrates. Other members of this superfamily include phosphoglucosamine mutase (PNGM), phosphoacetylglucosamine mutase (PAGM), the bacterial phosphomannomutase ManB, the bacterial phosphoglucosamine mutase GlmM, and the bifunctional phosphomannomutase/phosphoglucomutase (PMM/PGM). Each of these enzymes has four domains with a centrally located active site formed by four loops, one from each domain. All four domains are included in this alignment model.

phosphoglucomutase-2-like protein; Provisional

maltodextrin glucosidase; Provisional

Phosphomannomutase [Carbohydrate transport and metabolism].

ChainA, ALPHA AMYLASE II [Thermoactinomyces vulgaris],1JF6_B Chain B, ALPHA AMYLASE II [Thermoactinomyces vulgaris]

Alpha-amylaseIi (tvaii) From Thermoactinomyces Vulgaris R-47 [Thermoactinomyces vulgaris],1BVZ_B Alpha-amylase Ii (tvaii) From Thermoactinomyces Vulgaris R-47 [Thermoactinomyces vulgaris],1JI2_A Improved X-ray Structure of Thermoactinomyces vulgaris R-47 alpha-Amylase 2 [Thermoactinomyces vulgaris],1JI2_B Improved X-ray Structure of Thermoactinomyces vulgaris R-47 alpha-Amylase 2 [Thermoactinomyces vulgaris],3A6O_A Crystal structure of Thermoactinomyces vulgaris R-47 alpha-amylase 2/acarbose complex [Thermoactinomyces vulgaris],3A6O_B Crystal structure of Thermoactinomyces vulgaris R-47 alpha-amylase 2/acarbose complex [Thermoactinomyces vulgaris]

ChainA, Alpha-amylase II [Thermoactinomyces vulgaris],1WZM_B Chain B, Alpha-amylase II [Thermoactinomyces vulgaris]

ChainA, ALPHA AMYLASE II [Thermoactinomyces vulgaris],1JF5_B Chain B, ALPHA AMYLASE II [Thermoactinomyces vulgaris]

ChainA, Alpha-amylase II [Thermoactinomyces vulgaris],1WZK_B Chain B, Alpha-amylase II [Thermoactinomyces vulgaris]

Phosphoglucomutase OS=Bacillus subtilis (strain 168) OX=224308 GN=pgcA PE=1 SV=3

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

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

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

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