ENZYME entry: EC 3.2.1.140

Accepted Name
Lacto-N-biosidase.
Alternative Name(s)
Oligosaccharide lacto-N-biosylhydrolase.
Reaction catalysed
  • Beta-D-Gal-(1->3)-beta-D-GlcNAc-(1->3)-beta-D-Gal-(1->4)-D-Glc + H(2)O <=> beta-D-Gal-(1->3)-D-GlcNAc + beta-D-Gal-(1->4)-D-Glc
  • Lacto-N-tetraose + H(2)O <=> lacto-N-biose + lactose
Comment(s)
  • The enzyme from Streptomyces specifically hydrolyzes the terminal lacto-N-biosyl residue (beta-D-Gal-(1->3)-D-GlcNAc) from the non- reducing end of oligosaccharides with the structure beta-D-Gal- (1->3)-beta-D-GlcNAc-(1->3)-beta-D-Gal-(1->R).
  • Lacto-N-hexaose (beta-D-Gal-(1->3)-beta-D-GlcNAc-(1->3)-beta-D-Gal- (1->3)-beta-D-GlcNAc-(1->3)-beta-D-Gal-(1->4)-D-Glc) is hydrolyzed to form first lacto-N-tetraose plus lacto-N-biose, with the subsequent formation of lactose.
  • Oligosaccharides in which the non-reducing terminal Gal or the penultimate GlcNAc are replaced by fucose or sialic acid are not substrates.
  • Asialo GM1 tetraose (beta-D-Gal-(1->3)-beta-D-GalNAc-(1->3)-beta-D- Gal-(1->4)-D-Glc) is hydrolyzed very slowly, but lacto-N-neotetraose (beta-D-Gal-(1->4)-beta-D-GalNAc-(1->3)-beta-D-Gal-(1->4)-D-Glc) is not a substrate.
Cross-references
BRENDA3.2.1.140
EC2PDB3.2.1.140
ExplorEnz3.2.1.140
PRIAM enzyme-specific profiles3.2.1.140
KEGG Ligand Database for Enzyme Nomenclature3.2.1.140
IUBMB Enzyme Nomenclature3.2.1.140
IntEnz3.2.1.140
MEDLINEFind literature relating to 3.2.1.140
MetaCyc3.2.1.140

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