This domain is the catalytic region of the bacterial glycosyl-hydrolase family 97. This central part of the GH97 family protein sequences represents a typical and complete (beta/alpha)8-barrel or catalytic TIM-barrel type domain. The N- and C-terminal parts of the sequences, mainly consisting of beta-strands, form two additional non-catalytic domains [1]. In all known glycosidases with the (beta-alpha)8-barrel fold, the amino acid residues at the active site are located on the C-termini of the beta-strands [2,3].

1: GH97 is a new family of glycoside hydrolases, which is related to the alpha-galactosidase superfamily. Naumoff DG; BMC Genomics. 2005;6:112. PMID:16131397

2: Divergence of catalytic mechanism within a glycosidase family provides insight into evolution of carbohydrate metabolism by human gut flora. Gloster TM, Turkenburg JP, Potts JR, Henrissat B, Davies GJ; Chem Biol. 2008;15:1058-1067. PMID:18848471

3: Structural and functional analysis of a glycoside hydrolase family 97 enzyme from Bacteroides thetaiotaomicron. Kitamura M, Okuyama M, Tanzawa F, Mori H, Kitago Y, Watanabe N, Kimura A, Tanaka I, Yao M; J Biol Chem. 2008;283:36328-36337. PMID:18981178