Virulence of pathogenic organisms such as the Gram-positive Streptococcus pneumoniae is largely determined by the ability to degrade host glycoproteins and to metabolise the resultant carbohydrates. This family is the enzymatic region, EC:3.2.1.97, of the cell surface proteins that specifically cleave Gal-beta-1,3-GalNAc-alpha-Ser/Thr (T-antigen, galacto-N-biose), the core 1 type O-linked glycan common to mucin glycoproteins. This reaction is exemplified by the S. pneumoniae protein Swiss:B2DRU5, where Asp764 is the catalytic nucleophile-base and Glu796 the catalytic proton donor.

1: Mechanistic investigation of the endo-alpha-N-acetylgalactosaminidase from Streptococcus pneumoniae R6. Willis LM, Zhang R, Reid A, Withers SG, Wakarchuk WW; Biochemistry. 2009;48:10334-10341. PMID:19788271

2: Gh101 family of glycoside hydrolases: subfamily structure and evolutionary connections with other families. Naumoff DG; J Bioinform Comput Biol. 2010;8:437-451. PMID:20556855