Structure and dynamics of porcine submaxillary mucin as determined by natural abundance carbon-13 NMR spectroscopy
Nearly all of the resonances in the /sup 13/C NMR spectrum of porcine submaxillary mucin glycoprotein (PSM) have been assigned to the peptide core carbons and to the carbons in the eight different oligosaccharide side chains that arise from the incomplete biosynthesis of the sialylated A blood group pentasaccharide. By use of these assignments, a nearly complete structural analysis of intact PSM has been performed without resorting to degradative chemical methods. Considerable structural variability in the carbohydrate side chains was observed between mucins obtained from different animals, while no variability was observed between glands in a single animal. The dynamics of the PSM core and carbohydrate side chains were examined by using the carbon-13 nuclear magnetic resonance relaxation times and nuclear Overhauser enhancements of each assigned carbon resonance. The peptide core of PSM exhibits internal segmental flexibility that is virtually identical with that of ovine submaxillary mucin (OSM), whose carbohydrate side chain consists of the ..cap alpha..-NeuNAc(2-6)..cap alpha..-Ga1NAc disaccharide. These results differ from most reports of glycoprotein dynamics, which typically find the terminal carbohydrate residues to be undergoing rapid internal rotation about their terminal glycosidic bonds. The results reported here are consistent with previous studies on the conformations of the A and H determinants derived from model oligosaccharides and further indicate that the conformations of these determinants are unchanged when covalently bound to the mucin peptide core. In spite of their carbohydrate side-chain heterogeneity, mucins appear to be ideal glycoproteins for the study of O-linked oligosaccharide conformation and dynamics and for the study of the effects of glycosylation on polypeptide conformation and dynamics.
- Research Organization:
- Case Western Research Univ., Cleveland, OH
- OSTI ID:
- 5941094
- Journal Information:
- Biochemistry; (United States), Vol. 26:15
- Country of Publication:
- United States
- Language:
- English
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GLUCOPROTEINS
MOLECULAR STRUCTURE
NUCLEAR MAGNETIC RESONANCE
CARBON 13
OLIGOSACCHARIDES
SWINE
ANIMALS
CARBOHYDRATES
CARBON ISOTOPES
DOMESTIC ANIMALS
EVEN-ODD NUCLEI
ISOTOPES
LIGHT NUCLEI
MAGNETIC RESONANCE
MAMMALS
NUCLEI
ORGANIC COMPOUNDS
PROTEINS
RESONANCE
SACCHARIDES
STABLE ISOTOPES
VERTEBRATES
550601* - Medicine- Unsealed Radionuclides in Diagnostics