Endo-β-Galactosidase (NEB #P0777S) is an endoglycosidase, whereas β1-4 Galactosidase (NEB #P0730S), β1-4 Galactosidase S (NEB #P0745S), and β1-3,4 Galactosidase (NEB #P0746S) are exoglycosidases.
These enzymes are derived from different organisms and target distinct substrates. Endo-β-Galactosidase is cloned from Flavobacterium keratolyticus, β1-4 Galactosidase from Bacteroides fragilis, β1-4 Galactosidase S from Streptococcus pneumoniae, and β1-3,4 Galactosidase (BTG) from bovine testis.
Endo-β-Galactosidase cleaves internal β(1-4)-galactose linkages within poly-N-acetyllactosamine structures [Galβ(1-4)-↓-GlcNAcβ(1-3)]. In contrast, β1-4 Galactosidase and β1-4 Galactosidase S cleave external galactose residues via β(1-4) linkages, while β1-3,4 Galactosidase (BTG) cleaves external galactose residues linked via both β(1-3) and β(1-4) linkages.
