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Unusual anionic N-linked oligosaccharides from bovine lung
K E Norgard-Sumnicht1, L Roux, D K Toomre
1Glycobiology Program, University of California at San Diego, USA.
The Journal of Biological Chemistry
|November 17, 1995
Summary
Researchers discovered novel anionic N-linked oligosaccharides in bovine lung, differing from conventional structures. These complex sugar chains, particularly Class II, contain glycosaminoglycans and unique modifications, warranting further investigation in mammalian tissues.
Area of Science:
- Glycobiology
- Biochemistry
- Mammalian Physiology
Background:
- Previous work identified sulfated anionic N-linked oligosaccharides in endothelial cells.
- Mammalian lungs are rich in endothelial cells, suggesting potential for similar molecules.
Purpose of the Study:
- To investigate N-linked oligosaccharides in bovine lung.
- To characterize novel anionic sugar chains and their structures.
Main Methods:
- Enzymatic release of N-linked oligosaccharides using peptide: N-glycosidase F (PNGaseF).
- Radiolabeling with [3H]NaBH4 and analysis of anionic fractions.
- Biochemical treatments including enzymatic digestion (beta-glucuronidase, alpha-iduronidase) and compositional analysis.
Main Results:
- Two classes of anionic N-linked oligosaccharides (Class I and Class II) were identified.
- Class I chains showed properties of complex-type chains but with multiple carboxylic acid groups instead of sialic acids.
- Class II chains were highly charged due to glycosaminoglycans (chondroitin sulfate, heparin/heparan sulfate, keratan sulfate) and contained xylose residues not at the reducing terminus.
Conclusions:
- Bovine lung contains a high proportion of novel anionic N-linked oligosaccharides distinct from conventional structures.
- These findings suggest previously undescribed modifications in mammalian oligosaccharides.
- Further exploration of N-linked chains in intact mammalian tissues is recommended.