ENZYME

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A new class EC 7, Translocases, has been added to the EC list. It will be part of ENZYME from release 2018_10. Read more about EC 7 here.

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
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
BRENDA	3.2.1.140
EC2PDB	3.2.1.140
ExplorEnz	3.2.1.140
PRIAM enzyme-specific profiles	3.2.1.140
KEGG Ligand Database for Enzyme Nomenclature	3.2.1.140
IUBMB Enzyme Nomenclature	3.2.1.140
IntEnz	3.2.1.140
MEDLINE	Find literature relating to 3.2.1.140
MetaCyc	3.2.1.140