Substrate specificity of human liver neutral α-mannosidase
| Autor: | Peter F. Daniel, Christopher D. Warren, R De Gasperi, S al Daher, Bryan Winchester, S Hirani |
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| Rok vydání: | 1992 |
| Předmět: |
Glycan
Stereochemistry Molecular Sequence Data Oligosaccharides Mannose alpha-Mannosidase Biochemistry Substrate Specificity Hydrolysis chemistry.chemical_compound Mannosidases Carbohydrate Conformation Humans Molecular Biology Chromatography High Pressure Liquid chemistry.chemical_classification biology Catabolism Cell Biology Oligosaccharide Cytosol Enzyme Carbohydrate Sequence Liver chemistry biology.protein Research Article |
| Zdroj: | Biochemical Journal. 286:47-53 |
| ISSN: | 1470-8728 0264-6021 |
| DOI: | 10.1042/bj2860047 |
| Popis: | The digestion of radiolabelled natural oligosaccharide substrates by human liver neutral alpha-mannosidase has been studied by h.p.l.c. and h.p.t.l.c. The high-mannose oligosaccharides Man9GlcNAc and Man8GlcNAc are hydrolysed by the enzyme by two distinct non-random routes to a common product of composition Man6GlcNAc, which is then slowly converted into a unique Man5GlcNAc oligosaccharide, Man alpha(1----2)Man alpha(1----2)Man alpha(1----3)[Man alpha (1----6)] Man beta(1----4)GlcNAc. These pathways are different from the processing and lysosomal catabolic pathways for these structures. In particular, the alpha(1----2)-linked mannose residues attached to the core alpha(1----3)-linked mannose residue are resistant to hydrolysis. The key processing intermediate, Man alpha(1----3)[Man alpha(1----6)]Man alpha(1----6)[Man alpha(1----3)] Man beta(1----4)GlcNAc, is not produced in the digestion of high-mannose glycans by the neutral alpha-mannosidase, but it is hydrolysed by the enzyme by a non-random route to Man beta(1----4)GlcNAc via the core structure Man alpha(1----3)[Man alpha(1----6)]Man beta(1----4)GlcNAc. In contrast with its ready hydrolysis by lysosomal alpha-mannosidase, the core alpha(1----3)-mannosidic linkage is quite resistant to hydrolysis by neutral alpha-mannosidase. The precise specificity of neutral alpha-mannosidase towards high-mannose oligosaccharides suggests that it has a role in the modification of such structures in the cytosol. |
| Databáze: | OpenAIRE |
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