Hydrolyses the 1,4-β-D-galactosyl linkages adjacent to 1,3-N-acetyl-α-D-glucosaminyl residues. Also acts on some non-sulfated oligosaccharides, but only acts on blood group substances when the 1,2-linked fucosyl residues have been removed (cf. EC 18.104.22.168 blood-group-substance endo-1,4-β-galactosidase).
Fukuda, M.N. and Matsumara, G. Endo-β-galactosidase of Escherichia freundii. Purification and endoglycosidic action on keratan sulfates, oligosaccharides, and blood group active glycoprotein. J. Biol. Chem.251 (1976) 6218–6225. [PMID: 135762]