1H-N.m.r. spectral assignments for two series of heparin-derived oligosaccharides.
Six heparin-derived oligosaccharides, ranging in size from di- to octa-saccharide and forming two closely related series differing in structure by the substitution of an unsulfated D-glucuronate for a 2-sulfated L-iduronate residue, have been characterized by 2-dimensional 1H-n.m.r. spectroscopy. In addition to providing new data on hexa- and octa-saccharides, several important changes to previously published data have been found for the two tetrasaccharides. The D-glucuronic acid H-5 proton is assigned to a resonance in the same region as resonances for the H-3 and H-4 D-glucuronate protons, rather than downfield from these resonances as earlier reported. The presence of D-glucuronic acid in the heparin sequence of the series-1 fragments affects the positions of neighboring D-glucosamine resonances, in particular shifting the anomeric proton signal in the preceding D-glucosamine 0.1-0.2 p.p.m. downfield. Resonances from the reducing-end D-glucosamines differ from internal D-glucosamine resonances both in relative position and in the degree of chemical shift difference between the H-6 and H-6' protons. This work illustrates the usefulness of two-dimensional techniques in determining heparin structure and emphasizes the need for direct analysis, rather than assignment by comparison to model compounds.
Horne
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A
Department of Biochemistry, Vanderbilt University School of Medicine, Nashville, TN 37232-0146.
Gettins
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P
D002240:Carbohydrate Sequence; D004187:Disaccharides / Q000737:chemistry*; D005944:Glucosamine / Q000737:chemistry; D005965:Glucuronates / Q000737:chemistry; D020723:Glucuronic Acid; D006493:Heparin / Q000737:chemistry*; D007067:Iduronic Acid / Q000737:chemistry; D009682:Magnetic Resonance Spectroscopy; D008969:Molecular Sequence Data; D009844:Oligosaccharides / Q000737:chemistry*; D014312:Trisaccharides / Q000737:chemistry*
D004187:Disaccharides; D005965:Glucuronates; D009844:Oligosaccharides; D014312:Trisaccharides; D007067:Iduronic Acid; D020723:Glucuronic Acid; D006493:Heparin; D005944:Glucosamine