N-terminal catalytic domain of a thermoactive alpha-amylase from Methanococcus jannaschii and similar proteins; glycoside hydrolase family 57 (GH57). The subfamily is represented by a thermostable alpha-amylase (MJA1, EC 3.2.1.1) encoded from the hyperthermophilic archaeon Methanococcus jannaschii locus, M J1611. MJA1 has a broad pH optimum 5.0-8.0. It exhibits extremely thermophilic alpha-amylase activity that catalyzes the hydrolysis of large sugar polymers with alpha-l,6 and alpha-l,4 linkages, and yields products including glucose polymers of 1-7 units. MJ1611 also encodes another alpha-amylase with catalytic features distinct from MJA1, which belongs to glycoside hydrolase family 13 (GH-13), and is not included here. This subfamily also includes many uncharacterized proteins found in bacteria and archaea.

Alpha-amylase/alpha-mannosidase, GH57 family [Carbohydrate transport and metabolism].

Glycosyl hydrolase family 57. This family includes alpha-amylase (EC:3.2.1.1), 4--glucanotransferase (EC:2.4.1.-) and amylopullulanase enzymes.

N-terminal catalytic domain of heat stable retaining glycoside hydrolase family 57. Glycoside hydrolase family 57(GH57) is a chiefly prokaryotic family with the majority of thermostable enzymes coming from extremophiles (many of these are archaeal hyperthermophiles), which exhibit the enzyme specificities of alpha-amylase (EC 3.2.1.1), 4-alpha-glucanotransferase (EC 2.4.1.25), amylopullulanase (EC 3.2.1.1/41), and alpha-galactosidase (EC 3.2.1.22). This family also includes many hypothetical proteins with uncharacterized activity and specificity. GH57s cleave alpha-glycosidic bonds by employing a retaining mechanism, which involves a glycosyl-enzyme intermediate, allowing transglycosylation.

N-terminal catalytic domain of alpha-galactosidase; glycoside hydrolase family 57 (GH57). Alpha-galactosidases (GalA, EC 3.2.1.22) catalyze the hydrolysis of alpha-1,6-linked galactose residues from oligosaccharides and polymeric galactomannans. Based on sequence similarity, the majority of eukaryotic and bacterial GalAs have been classified into glycoside hydrolase family GH27, GH36, and GH4, respectively. This subfamily is represented by a novel type of GalA from Pyrococcus furiosus (PfGalA), which belongs to the GH57 family. PfGalA is an extremely thermo-active and thermostable GalA that functions as a bacterial-like GalA, however, without the capacity to hydrolyze polysaccharides. It specifically catalyzes the hydrolysis of para-nitrophenyl-alpha-galactopyranoside, and to some extent that of melibiose and raffinose. PfGalA has a pH optimum between 5.0-5.5.

Putative alpha-amylase OS=Methanocaldococcus jannaschii (strain ATCC 43067 / DSM 2661 / JAL-1 / JCM 10045 / NBRC 100440) OX=243232 GN=MJ1611 PE=3 SV=1