Editing Clostridium perfringens (section)

==== Hexosaminidase ====
The mucus layer consists of intestinal mucin glycans, glycolipids, and glycoproteins that contain [[hexosamines]], such as [[N-Acetylglucosamine|N-acetylglucosamine]] (GlcNAc) and [[N-Acetylgalactosamine|N-acetylgalactosamine]] (GalNAc). ''C. perfringens'' encodes for eight [[hexosaminidase]]s that break down hexosamines in the mucus. These hexosaminidases belong to four glycoside hydrolase families: GH36, GH84, GH89, and GH123.<ref name=":022" />

''C. perfringens'' encodes for AagA (''Cp''GH36A) and ''Cp''GH36B in [[Glycoside hydrolase family 36|glycoside hydrolase family 36 (GH36)]]: AagA removes GalNAc from O-glycans, and ''Cp''GH36B is expected to have a similar structure to AagA, but specificities on its function are unknown. NagH, NagI, NagJ, and NagK, belonging to glycoside hydrolase family 84 (GH84), cleave terminal GlcNAc residues using a substrate-assisted digestion mechanism. AgnC (''Cp''GH89), belonging to [[glycoside hydrolase family 89]] (GH89), both cleaves GlcNAc from the ends of mucin glycans and acts on gastric mucin. Belonging to glycoside hydrolase family 123 (GH123), ''Cp''Nga123 cleaves GalNAc, but research suggests that it only breaks down glycans taken up by ''C. perfringens'' due to the absence of a secretion signal peptide.<ref name=":022" />