InterPro: IPR006589 Glycosyl hydrolase, family 13, subfamily, catalytic domain

O-Glycosyl hydrolases EC:3.2.1. are a widespread group of enzymes that hydrolyse the glycosidic bond between two or more carbohydrates, or between a carbohydrate and a non-carbohydrate moiety. A classification system for glycosyl hydrolases, based on sequence similarity, has led to the definition of 85 different families [1, 2, 3]. This classification is available on the CAZy (CArbohydrate-Active EnZymes) web site [4]. Because the fold of proteins is better conserved than their sequences, some of the families can be grouped in clans.

Enzymes containing this domain, such as alpha-amylase, belong to family 13 (GH13) of the glycosyl hydrolases. The maltogenic alpha-amylase is an enzyme which catalyses hydrolysis of (1-4)-alpha-D-glucosidic linkages in polysaccharides so as to remove successive alpha-maltose residues from the non-reducing ends of the chains in the conversion of starch to maltose. Other enzymes include neopullulanase, which hydrolyses pullulan to panose, and cyclomaltodextrinase, which hydrolyses cyclodextrins.

This entry represents the catalytic domain found in several protein members of this family, mainly in the EC:3.2.1 enzymes. It has a structure consisting of an 8 stranded alpha/beta barrel that contains the active site, interrupted by a ~70 amino acid calcium-binding domain protruding between beta strand 3 and alpha helix 3, and a carboxyl-terminal Greek key beta-barrel domain [5].

More information about this protein can be found at Protein of the Month: alpha-Amylase [6].