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Conformations of blood group H‐active oligosacharides of ovarian cyst mucins
Author(s) -
Rao B. N. Narasinga,
Dua Virendra K.,
Bush C. Allen
Publication year - 1985
Publication title -
biopolymers
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.556
H-Index - 125
eISSN - 1097-0282
pISSN - 0006-3525
DOI - 10.1002/bip.360241205
Subject(s) - chemistry , amide , dihedral angle , chemical shift , crystallography , stereochemistry , fucose , nmr spectra database , nuclear overhauser effect , proton nmr , galactose , nuclear magnetic resonance spectroscopy , spectral line , biochemistry , molecule , organic chemistry , hydrogen bond , astronomy , physics
Spectroscopic data and conformational energy calculations are reported for eight oligosaccharides from ovarian cyst mucins and from human milk, the nonreducing terminals of which have fucose (α1 → 2)galactose linked either (β1 → 3) (type I) or (β1 → 4)(type II) to N ‐acetylglucosamine or in (β1 → 3) linkage to galactosaminitol. The fully assigned proton nmr spectra are reported along with nuclear Overhauser enhancement (NOE) data. Amide proton coupling constants and vacuum‐uv CD spectra provide information on the amide plane orientation and amide environment. Our results imply that the fucosidic dihedral angles are similar for all three cases and that the substantial differences in the chemical shifts of the fucosyl protons of type I, type II, and 3‐ol chains result from different perturbations by the amide group of the residue to which the β‐galactose is linked. Stereopair diagrams of conformational models for both type I and II H chains are presented that are consistent with NOE, coupling constants, conformational energy calculations, and the CD data. While the temperature dependence of the observed NOE of penta‐ and hexasaccharides indicates that their rotational correlation times are strongly temperature dependent, we conclude that the conformations are essentially independent of temperature.