Blood-group-substance endo-1,4-ò-galactosidase (, endo-ò-galactosidase, blood-group-substance 1,4-ò-<small>D</small>-galactanohydrolase) is an enzyme with systematic name blood-group-substance 4-ò-<small>D</small>-galactanohydrolase. It catalyses endohydrolysis of (1âÂÂ4)-ò-<small>D</small>-galactosidic linkages in blood group A and B substances.
It hydrolyses the 1,4-ò-<small>D</small>-galactosyl linkages adjacent to a 1,3-ñ-<small>D</small>-galactosyl or N-acetylgalactosaminyl residues and a 1,2-ñ-<small>D</small>-fucosyl residue.