EC - Lacto-N-biosidase

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IntEnz Enzyme Nomenclature


Accepted name:
Systematic name:
oligosaccharide lacto-N-biosylhydrolase



The enzyme from Streptomyces specifically hydrolyses the terminal lacto-N-biosyl residue (β-D-Gal-(1→3)-D-GlcNAc) from the non-reducing end of oligosaccharides with the structure β-D-Gal-(1→3)-β-D-GlcNAc-(1→3)-β-D-Gal-(1→R). Lacto-N-hexaose (β-D-Gal-(1→3)-β-D-GlcNAc-(1→3)-β-D-Gal-(1→3)-β-D-GlcNAc-(1→3)-β-D-Gal-(1→4)-D-Glc) is hydrolysed 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 (β-D-Gal-(1→3)-β-D-GalNAc-(1→3)-β-D-Gal-(1→4)-D-Glc) is hydrolysed very slowly, but lacto-N-neotetraose (β-D-Gal-(1→4)-β-D-GalNAc-(1→3)-β-D-Gal-(1→4)-D-Glc) is not a substrate.

Links to other databases

Enzymes and pathways: NC-IUBMB , BRENDA , ExplorEnz , ENZYME@ExPASy , KEGG , MetaCyc , UniPathway
Structural data: CSA , EC2PDB
Gene Ontology: GO:0047403


  1. Sano, M., Hayakawa, K., Kato, I.
    An enzyme releasing lacto-N-biose from oligosaccharides.
    Proc. Natl. Acad. Sci. USA 89: 8512-8516 (1992). [PMID: 1528855]
  2. Sano, M., Hayakawa, K., Kato, I.
    Purification and characterization of an enzyme releasing lacto-N-biose from oligosaccharides with type 1 chain.
    J. Biol. Chem. 268: 18560-18566 (1993). [PMID: 7689556]

[EC created 1999]