This family is recognised as a glycosyl-hydrolase family, number 114. It is endo-alpha-1,4-polygalactosaminidase, a rare enzyme. It is proposed to be TIM-barrel, the most common structure amongst the catalytic domains of glycosyl-hydrolases [1].

1: [Endo-alpha-1-4-polygalactosaminidases and their homologues: structure and evolution]. Naumov DG, Stepushchenko OO; Mol Biol (Mosk). 2011;45:703-714. PMID:21954604