Glucosyl residues

Measured ar 400 MHz in D20 referenced to internal r-BuOH (1.203 ppm.) Assignments for glucosyl residues. 

Deoxyfluorostarches were prepared from com starch by treatment of the tosylated (mostly at 0-6 of the o-glucosyl residues) starch precursors with KF in ethylene glycol (190°, 15 min) or by treatment of starch with hydrofluoric acid (Mc2SO, —30°, 4 h — room temp., 10 min). 

The amino sugar counterparts of D-glucuronic acid and nonsulfated L-iduronic acid in heparin are either N-acetylated, or nonsulfated at C-6, or both. 2-Acetamido-2-deoxy-D-glucosyl residues account for only a minor proportion of the total hexosamine in heparin, and are especially low in beef-lung preparations (see Table II).8,138,147 -149 In contrast, they... 

Whereas a major proportion of the 2-acetamido-2-deoxy-D-glucosyl residues is probably nonsulfated at C-6 (C-sulfation is expected to require prior N-sulfation),23 various degrees of C-sulfation have been reported for N-acetylated regions of heparan sulfates,148,149 and a 6-C-sul-fated, N-acetylated disaccharide was isolated from heparanase digests of heparan sulfates.114,115... 

The scope of the deamination reaction was extended to the characterization of heparin segments containing 2-acetamido-2-deoxy-D-glucosyl residues by removing (by hydrazinolysis) the N-acetyl groups and cleaving with nitrous acid (at pH 4) the otherwise resistant segments.113,232... 

As a result of these studies, tentative structure 41 for a repeating unit of S37 was proposed. Eventually, some residues could have a second sophorosyl end-group, linked to the other (1 — 3)-linked D-glucosyl residue in 41, a proposal that the present authors consider... 

FIG. 25.—(A) 13C-N.m.r. Spectrum of Heparin in D20 at Ambient Temperature. (I-Signals are ascribed to a-L-idosyluronic acid residues, and G-signals to 2-amino-2-deoxy-a-D-glucosyl residues chemical shifts are expressed as 8C, relative to external tetramethylsilane.) (B) 13C-N.m.r. Spectrum of Dermatan Sulfate in D20 at 70°. (The horizontal axis is based on 8C, relative to external CS2.)... 

Keratan sulfate consists of a (l—>3)-0-/3-D-galactopyranosyl-(l— 4)-0-2-acetamido-2-deoxy-/3-D-glucopyranosy 1 repeating-unit containing 40% of galactosyl residues and >70% of 2-acetamido-2-deoxy-D-glucosyl residues esterified at C-6 by sulfate. 

Number of D-glucosyl residues Name Molecular weight Solubility in water (g/100 mL) Cavity width (pm) ... 

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