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EC | 3.2.1.140 | ||||
Accepted name: | lacto-N-biosidase | ||||
Reaction: | β-D-Gal-(1→3)-β-D-GlcNAc-(1→3)-β-D-Gal-(1→4)-D-Glc + H2O = β-D-Gal-(1→3)-D-GlcNAc + β-D-Gal-(1→4)-D-Glc | ||||
Glossary: | β-D-Gal-(1→3)-β-D-GlcNAc-(1→3)-β-D-Gal-(1→4)-D-Glc = lacto-N-tetraose β-D-Gal-(1→3)-D-GlcNAc = lacto-N-biose β-D-Gal-(1→4)-D-Glc = lactose |
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Systematic name: | oligosaccharide lacto-N-biosylhydrolase | ||||
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: | BRENDA, EXPASY, KEGG, MetaCyc, PDB, CAS registry number: 146359-52-6 | ||||
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