Alpha amylase catalytic domain family; 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; and 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 this 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.

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gi 71994722 284 FILHWLAGHVPNLRRFRFVCFCYPEVVDYILNEIQH---------FKWDANRRA 328
Cdd:cd14791 103 WLLKDPGGPPVTGRNQYVLDLSNPEVRDYLREVIDRllrewgidyLKWDFNRAG 156

glycosyl hydrolase family 36 (GH36); GH36 enzymes occur in prokaryotes, eukaryotes, and archaea with a wide range of hydrolytic activities, including alpha-galactosidase, alpha-N-acetylgalactosaminidase, stachyose synthase, and raffinose synthase. All GH36 enzymes cleave a terminal carbohydrate moiety from a substrate that varies considerably in size, depending on the enzyme, and may be either a starch or a glycoprotein. GH36 members are retaining enzymes that cleave their substrates via an acid/base-catalyzed, double-displacement mechanism involving a covalent glycosyl-enzyme intermediate. Two aspartic acid residues have been identified as the catalytic nucleophile and the acid/base, respectively.

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                ....*....|....*....|....*....|....*....|....*....|....
gi 71994722 284 FILHWLAGHVPNLRRFRFVCFCYPEVVDYILNEIQH---------FKWDANRRA 328
Cdd:cd14791 103 WLLKDPGGPPVTGRNQYVLDLSNPEVRDYLREVIDRllrewgidyLKWDFNRAG 156

glycosyl hydrolase family 36 (GH36); GH36 enzymes occur in prokaryotes, eukaryotes, and archaea with a wide range of hydrolytic activities, including alpha-galactosidase, alpha-N-acetylgalactosaminidase, stachyose synthase, and raffinose synthase. All GH36 enzymes cleave a terminal carbohydrate moiety from a substrate that varies considerably in size, depending on the enzyme, and may be either a starch or a glycoprotein. GH36 members are retaining enzymes that cleave their substrates via an acid/base-catalyzed, double-displacement mechanism involving a covalent glycosyl-enzyme intermediate. Two aspartic acid residues have been identified as the catalytic nucleophile and the acid/base, respectively.

                        10        20        30        40        50
                ....*....|....*....|....*....|....*....|....*....|....
gi 71994722 284 FILHWLAGHVPNLRRFRFVCFCYPEVVDYILNEIQH---------FKWDANRRA 328
Cdd:cd14791 103 WLLKDPGGPPVTGRNQYVLDLSNPEVRDYLREVIDRllrewgidyLKWDFNRAG 156