InterPro: IPR011613 Glycoside hydrolase 15-related

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.

Glycoside hydrolase family 15 GH15 comprises enzymes with several known activities; glucoamylase (EC:3.2.1.3); alpha-glucosidase (EC:3.2.1.20); glucodextranase (EC:3.2.1.70).

Glucoamylase (GA) catalyses the release of D-glucose from the non-reducing ends of starch and other oligo- or poly-saccharides. Studies of fungal GA have indicated 3 closely-clustered acidic residues that play a role in the catalytic mechanism [5]. This region is also conserved in a recently sequenced bacterial GA [6].

The 3D structure of the pseudo-tetrasaccharide acarbose complexed with glucoamylase II(471) from Aspergillus awamori var. X100 has been determined to 2.4A resolution [7]. The protein belongs to the mainly-alpha class, and contains 19 helices and 9 strands.