trehalose-6-phosphate hydrolase; Provisional

Alpha amylase catalytic domain found in Sucrose isomerases, oligo-1,6-glucosidase (also called isomaltase; sucrase-isomaltase; alpha-limit dextrinase), dextran glucosidase (also called glucan 1,6-alpha-glucosidase), and related proteins. The sucrose isomerases (SIs) Isomaltulose synthase (EC 5.4.99.11) and Trehalose synthase (EC 5.4.99.16) catalyze the isomerization of sucrose and maltose to produce isomaltulose and trehalulose, respectively. Oligo-1,6-glucosidase (EC 3.2.1.10) hydrolyzes the alpha-1,6-glucosidic linkage of isomaltooligosaccharides, pannose, and dextran. Unlike alpha-1,4-glucosidases (EC 3.2.1.20), it fails to hydrolyze the alpha-1,4-glucosidic bonds of maltosaccharides. Dextran glucosidase (DGase, EC 3.2.1.70) hydrolyzes alpha-1,6-glucosidic linkages at the non-reducing end of panose, isomaltooligosaccharides and dextran to produce alpha-glucose.The common reaction chemistry of the alpha-amylase family enzymes is based on a two-step acid catalytic mechanism that requires two critical carboxylates: one acting as a general acid/base (Glu) and the other as a nucleophile (Asp). Both hydrolysis and transglycosylation proceed via the nucleophilic substitution reaction between the anomeric carbon, C1 and a nucleophile. Both enzymes contain the three catalytic residues (Asp, Glu and Asp) common to the alpha-amylase family as well as two histidine residues which are predicted to be critical to binding the glucose residue adjacent to the scissile bond in the substrates. 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 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.

alpha,alpha-phosphotrehalase. Trehalose is a glucose disaccharide that serves in many biological systems as a compatible solute for protection against hyperosmotic and thermal stress. This family describes trehalose-6-phosphate hydrolase, product of the treC (or treA) gene, which is often found together with a trehalose uptake transporter and a trehalose operon repressor.

Alpha amylase catalytic domain found in oligo-1,6-glucosidase (also called isomaltase; sucrase-isomaltase; alpha-limit dextrinase) and related proteins. Oligo-1,6-glucosidase (EC 3.2.1.10) hydrolyzes the alpha-1,6-glucosidic linkage of isomalto-oligosaccharides, pannose, and dextran. Unlike alpha-1,4-glucosidases (EC 3.2.1.20), it fails to hydrolyze the alpha-1,4-glucosidic bonds of maltosaccharides. 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.

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.

Structureof glucan-1,6-alpha-glucosidase from Lactobacillus acidophilus NCFM [Lactobacillus acidophilus NCFM]

ChainA, Dextran glucosidase [unidentified]

Structureof dextran glucosidase with glucose [Streptococcus mutans UA159],4XB3_A Structure of dextran glucosidase [Streptococcus mutans UA159]

ChainA, Dextran glucosidase [unidentified]

CrystalStructure Of B. Cereus Oligo-1,6-Glucosidase [Bacillus cereus]

Glucan 1,6-alpha-glucosidase OS=Streptococcus pneumoniae serotype 4 (strain ATCC BAA-334 / TIGR4) OX=170187 GN=dexB PE=3 SV=2

Glucan 1,6-alpha-glucosidase OS=Streptococcus dysgalactiae subsp. equisimilis OX=119602 GN=dexB PE=3 SV=1

Oligo-1,6-glucosidase OS=Alkalihalobacillus halodurans (strain ATCC BAA-125 / DSM 18197 / FERM 7344 / JCM 9153 / C-125) OX=272558 GN=malL PE=3 SV=1

Glucan 1,6-alpha-glucosidase OS=Streptococcus mutans serotype c (strain ATCC 700610 / UA159) OX=210007 GN=dexB PE=1 SV=2

Oligo-1,6-glucosidase OS=Bacillus cereus OX=1396 GN=malL PE=1 SV=1