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.

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

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

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 thermoactive amylopullulanases; glycoside hydrolase family 57 (GH57). Pullulanases (EC 3.2.1.41) are capable of hydrolyzing the alpha-1,6 glucosidic bonds of pullulan, producing maltotriose. Amylopullulanases (APU, E.C 3.2.1.1/41) are type II pullulanases which can also degrade both the alpha-1,6 and alpha-1,4 glucosidic bonds of starch, producing oligosaccharides. This subfamily includes GH57 archaeal thermoactive APUs, which show both pullulanolytic and amylolytic activities. They have an acid pH optimum and the presence of Ca2+ might increase their activity, thermostability, and substrate affinity. Besides GH57 thermoactive APUs, all mesophilic and some thermoactive APUs belong to glycoside hydrolase family 13 with catalytic features distinct from GH57. This subfamily also includes many uncharacterized proteins found in bacteria and archaea.

Crystalstructure of 4-alpha-glucanotransferase from thermococcus litoralis [Thermococcus litoralis],1K1X_B Crystal structure of 4-alpha-glucanotransferase from thermococcus litoralis [Thermococcus litoralis],1K1Y_A Crystal structure of thermococcus litoralis 4-alpha-glucanotransferase complexed with acarbose [Thermococcus litoralis],1K1Y_B Crystal structure of thermococcus litoralis 4-alpha-glucanotransferase complexed with acarbose [Thermococcus litoralis]

Crystalstructure of 4-alpha-glucanotransferase from thermococcus litoralis [Thermococcus litoralis]

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

Alpha-amylase OS=Pyrococcus horikoshii (strain ATCC 700860 / DSM 12428 / JCM 9974 / NBRC 100139 / OT-3) OX=70601 GN=amyA PE=3 SV=1

4-alpha-glucanotransferase OS=Thermococcus litoralis (strain ATCC 51850 / DSM 5473 / JCM 8560 / NS-C) OX=523849 GN=jgt PE=1 SV=1

Alpha-amylase OS=Pyrococcus abyssi (strain GE5 / Orsay) OX=272844 GN=amyA PE=3 SV=1

Alpha-amylase OS=Pyrococcus furiosus (strain ATCC 43587 / DSM 3638 / JCM 8422 / Vc1) OX=186497 GN=amyA PE=1 SV=2