This family includes the following three closely related glycosyl hydrolase family 31 (GH31) enzymes: maltase-glucoamylase (MGAM), sucrase-isomaltase (SI), and lysosomal acid alpha-glucosidase (GAA), also known as acid-maltase. MGAM is one of the two enzymes responsible for catalyzing the last glucose-releasing step in starch digestion. SI is implicated in the digestion of dietary starch and major disaccharides such as sucrose and isomaltose, while GAA degrades glycogen in the lysosome, cleaving both alpha-1,4 and alpha-1,6 glucosidic linkages. MGAM and SI are anchored to small-intestinal brush-border epithelial cells. The absence of SI from the brush border membrane or its malfunction is associated with malabsorption disorders such as congenital sucrase-isomaltase deficiency (CSID). The domain architectures of MGAM and SI include two tandem GH31 catalytic domains, an N-terminal domain found near the membrane-bound end, and a C-terminal luminal domain. Both of the tandem GH31 domains of MGAM and SI are included in this family. The domain architecture of GAA includes an N-terminal TFF (trefoil factor family) domain in addition to the GH31 catalytic domain. Deficient GAA expression causes pompe disease, an autosomal recessive genetic disorder also known as glycogen storage disease type II (GSDII).

Glycosyl hydrolases family 31. Glycosyl hydrolases are key enzymes of carbohydrate metabolism. Family 31 comprises of enzymes that are, or similar to, alpha- galactosidases.

This family includes the following three closely related glycosyl hydrolase family 31 (GH31) enzymes: maltase-glucoamylase (MGAM), sucrase-isomaltase (SI), and lysosomal acid alpha-glucosidase (GAA), also known as acid-maltase. MGAM is one of the two enzymes responsible for catalyzing the last glucose-releasing step in starch digestion. SI is implicated in the digestion of dietary starch and major disaccharides such as sucrose and isomaltose, while GAA degrades glycogen in the lysosome, cleaving both alpha-1,4 and alpha-1,6 glucosidic linkages. MGAM and SI are anchored to small-intestinal brush-border epithelial cells. The absence of SI from the brush border membrane or its malfunction is associated with malabsorption disorders such as congenital sucrase-isomaltase deficiency (CSID). The domain architectures of MGAM and SI include two tandem GH31 catalytic domains, an N-terminal domain found near the membrane-bound end, and a C-terminal luminal domain. Both of the tandem GH31 domains of MGAM and SI are included in this family. The domain architecture of GAA includes an N-terminal TFF (trefoil factor family) domain in addition to the GH31 catalytic domain. Deficient GAA expression causes pompe disease, an autosomal recessive genetic disorder also known as glycogen storage disease type II (GSDII).

Glycosyl hydrolases family 31. Glycosyl hydrolases are key enzymes of carbohydrate metabolism. Family 31 comprises of enzymes that are, or similar to, alpha- galactosidases.

Alpha-glucosidase II (alpha-D-glucoside glucohydrolase) is a glycosyl hydrolase family 31 (GH31) enzyme, found in bacteria and plants, which has exo-alpha-1,4-glucosidase and oligo-1,6-glucosidase activities. Alpha-glucosidase II has been characterized in Bacillus thermoamyloliquefaciens where it forms a homohexamer. This family also includes the MalA alpha-glucosidase from Sulfolobus sulfataricus and the AglA alpha-glucosidase from Picrophilus torridus. MalA is part of the carbohydrate-metabolizing machinery that allows this organism to utilize carbohydrates, such as maltose, as the sole carbon and energy source.