13C nuclear magnetic resonance spectra of glucobioses, glucotrioses, and glucans

Abstract

Natural-abundance carbon-I 3 n.m.r. spectra of all the glucobioses and of four selected glucotrioses in aqueous solution have been measured and are discussed. Peak assignments were made on the basis of comparison with the spectra of methyl glucopyranosides, four mono-0-methylglucoses and five methyl glucobiosides. Carbon-I 3 n.m.r. spectroscopy proved to be a useful tool for stereochemical characterisation of these oligosaccharides. In addition, carbon-I 3 n.m.r. spectra of the a-limit dextrins from glycogen and amylopectin have been measured and the differences between them are discussed.SPECTROMETRIC methods (i.r.,l o.r.d.,2 and lH n.m.r.3~4) have been used for establishing the configuration of glycosidic linkages of oligosaccharides and polysaccharides. The Karplus equation in lH n.m.r. has been applied extensively in the structural studies of monosaccharide pyranose and furanose derivatives.5 Positions of linkage in oligosaccharides have been determined by chemical methods and by biochemical degradation.+lO Recently, the 13C n.m.r. spectra of monosaccharides 11,12 and some common oligosaccharides 13*14 have been published and interpreted. These reports show that 13C chemical shift differences in sugars could be explained in terms of steric hindrance and proximity effectsWe have already reported that 13C n.m.r. spectroscopy can be used for the determination of the anomeric configurations of glucobi~ses.~~ We now describe the application of 13C n.m.r. to the configurational and conformational analysis of glucose oligomers and polymers, as well as to the determination of their linkage positions. Some tentative assignments l5 arc corrected on the basis of further data reported here. RESULTS AND DISCUSSIONIn 13C n.m.r. spectroscopy, it is difficult and laborious t o give a full peak assignment of sugar carbon atoms, although information from previous work has made it considerably ~imp1er.ll-l~ Roberts and his co-workers l1 showed that (a) methylation of a hydroxy-group effects

Role of Ethanol in Improvement of Bacterial Cellulose Production: Analysis Using 13C-Labeled Carbon Sources

“…A11 of the 13C signals for each carbon of glucose were assigned as shown in Fig. 6, according to a previous report (Usui et al , 1973). In the 13C NMR spectra of the glucose units from the 13C-labeled BC, some peaks were apparently enhanced (Fig.…”

Experimental chemical shift correlation maps from heteronuclear two-dimensional nuclear magnetic resonance spectroscopy. II: Carbon-13 and proton chemical shifts of a-D-glucopyranose oligomers

“…Several assignments have been proposed for maltose (2) and maltotriose (3) (16,19,20), but the experimental results obtained suggest a minor adjustment to the assignment of maltose, and a fairly radical reinterpretation of the 'During the reparation of this paper Heyraud el ,a/. the C-2' and C-5' assignmenis is borne out by the (Biopolymers, 18, 167 (1979)) have published carbon-13 assignments for maltose and maltotriose identical to those derived of the reassigned C-2' here; we thank a referee for drawing this paper to our attention.…”

Carbon-13 Nuclear Magnetic Resonance Spectra of Phenolic Glycosides Isolated from Chestnut Galls

“…The peak at 103.7 ppm is attributed to the C-I' signal in fi-linkage and the peak at 64.8 ppm can be assigned to C-6' carrying a galloyl group based on the acylation effects. 7 ) Moreover, upfield shift of the C-5' peak is explained by the fi-effect of the C-6' substitution.…”