High-temperature enhancement of 13C-N.M.R. chemical-shifts of unusual dextrans,and correlation with methylation structural analysis |
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| Authors: | Fred R. Seymour Roger D. Knapp Stephen H. Bishop Allene Jeanes |
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| Affiliation: | Fleming Department of Rehabilitation, Baylor College of Medicine, Texas Medical Center, Houston, Texas 77030 U.S.A.;Division of Atherosclerosis and Lipoprotein Research, Baylor College of Medicine, and Methodist Hospital, Texas Medical Center, Houston, Texas 77030 U.S.A.;Marrs McLean Department of Biochemistry, Baylor College of Medicine, Texas Medical Center, Houston, Texas 77030 U.S.A.;Cereal Science and Foods Laboratory, Northern Regional Research Center, Peoria, Illinois 61604 U.S.A. |
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| Abstract: | Dextran fractions from NRRL strains Leuconostoc mesenteroides B-742, B-1299, B-1355, and Streptobacterium dextranicum B-1254 were examined by 13C-n.m.r. spectroscopy at 34 and 90°, and by methylation structural analysis. The native, structurally homogeneous dextran from L. mesenteroides NRRL B-1402 was also examined. The data allow correlations to be made between the structure and physical properties of the S (soluble) and L (less-soluble) fraction pairs of dextrans B-742, B-1254, B-1299, and B-1355. For the dextrans under consideration here, increasing solubility of the dextran (both in water and in aqueous ethanol) was found to correlate with decreasing percentages of α-d-(1→6)-linked d-glucopyranosyl residues. Both the diagnostic nature of the 70–75-p.p.m. spectral region with regard to type of dextran branching, and the increase in resolution of the polysaccharide spectra at higher temperatures, have been further confirmed. |
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