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.
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