ID 3.2.1.140 DE lacto-N-biosidase. AN oligosaccharide lacto-N-biosylhydrolase. CA beta-D-Gal-(1->3)-beta-D-GlcNAc-(1->3)-beta-D-Gal-(1->4)-D-Glc + H2O = CA beta-D-galactosyl-(1->3)-N-acetyl-D-glucosamine + lactose. CC -!- The enzyme from Streptomyces specifically hydrolyzes the terminal CC lacto-N-biosyl residue (beta-D-Gal-(1->3)-D-GlcNAc) from the non- CC reducing end of oligosaccharides with the structure beta-D-Gal- CC (1->3)-beta-D-GlcNAc-(1->3)-beta-D-Gal-(1->R). CC -!- Lacto-N-hexaose (beta-D-Gal-(1->3)-beta-D-GlcNAc-(1->3)-beta-D-Gal- CC (1->3)-beta-D-GlcNAc-(1->3)-beta-D-Gal-(1->4)-D-Glc) is hydrolyzed to CC form first lacto-N-tetraose plus lacto-N-biose, with the subsequent CC formation of lactose. CC -!- Oligosaccharides in which the non-reducing terminal Gal or the CC penultimate GlcNAc are replaced by fucose or sialic acid are not CC substrates. CC -!- Asialo GM1 tetraose (beta-D-Gal-(1->3)-beta-D-GalNAc-(1->3)-beta-D- CC Gal-(1->4)-D-Glc) is hydrolyzed very slowly, but lacto-N-neotetraose CC (beta-D-Gal-(1->4)-beta-D-GalNAc-(1->3)-beta-D-Gal-(1->4)-D-Glc) is CC not a substrate. DR B3TLD6, LNBB_BIFB1 ; P0DW93, LNBX_BIFL2 ; //