IntEnz

EC 3.2.1.140 - Lacto-N-biosidase

IntEnz Enzyme Nomenclature
EC 3.2.1.140

Names

Reaction

• 21568 [IUBMB]
  β-D-Gal-(1→3)-β-D-GlcNAc-(1→3)-β-D-Gal-(1→4)-D-Glc

  beta-D-Gal-(1->3)-beta-D-GlcNAc-(1->3)-beta-D-Gal-(1->4)-D-Glc

  Name origin: UniProt - CHECKED (C)

  CHEBI:30248

  Formula: C26H45NO21
  Charge: 0

  ChEBI compound status: CHECKED (C)

  

  +

  H₂O

  H2O

  Name origin: UniProt - CHECKED (C)

  CHEBI:15377

  Formula: H2O
  Charge: 0

  ChEBI compound status: CHECKED (C)

  

  <?>

  β-D-galactopyranosyl-(1→3)-N-acetyl-D-glucosamine

  beta-D-galactopyranosyl-(1->3)-N-acetyl-D-glucosamine

  Name origin: UniProt - CHECKED (C)

  CHEBI:27707

  Formula: C14H25NO11
  Charge: 0

  ChEBI compound status: CHECKED (C)

  

  +

  lactose

  lactose

  Name origin: UniProt - CHECKED (C)

  CHEBI:17716

  Formula: C12H22O11
  Charge: 0

  ChEBI compound status: CHECKED (C)

  

Comments:

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

References

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 3.2.1.140 created 1999]