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Pyranose

About: Pyranose is a research topic. Over the lifetime, 1619 publications have been published within this topic receiving 35348 citations. The topic is also known as: pyranoses & hexopyranose.


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Journal ArticleDOI
TL;DR: The T(g) value demonstrates that the amorphous sugar matrix, in which the segments are fixed by fewer hydrogen bonds, has a higher thermal resistance.
Abstract: Temperature scanning Fourier transform infrared, TS-FTIR, spectroscopy of various amorphous sugar matrixes was conducted to investigate the relationship between the glass transition temperature, T(g), of an amorphous sugar matrix and the nature of the hydrogen bonds in the matrix. An amorphous sugar matrix was prepared by air-drying an aqueous solution of sugar, and the degree of formation of hydrogen bonds in the matrix was evaluated at different temperatures using the peak positions of the IR band corresponding to the O-H stretching vibration at around 3400 cm(-1). The T(g) value increased with increasing peak position of the O-H stretching vibration at T(g) and were correlated reasonably well with the magnitude of the peak shift by the temperature increase (from 25 degrees C) to the T(g) value. This demonstrates that the amorphous sugar matrix, in which the segments are fixed by fewer hydrogen bonds, has a higher thermal resistance. The glycosidic linkage largely contributes to the restriction of the segments, pyranose ring, rather than a hydrogen bond. As the degree of polymerization of pyranose rings increases, the degree of hydrogen bond formation needed to hold the matrix in a fixed position decreases. However, the magnitude of the restriction of pyranose rings by a glycosidic linkage changes depending on the type: the restrictions imposed by alpha-1,1 and -1,6 glycosidic linkages are the tightest and most flexible of all of the types of glycosidic linkages, respectively.

62 citations

Journal ArticleDOI
TL;DR: It is tentatively postulated that inhibitory effects observed with aldonolactones on glycosidases of corresponding configuration may be due entirely to the (1-->5)-lactone, and that any inhibitory effect seen with the ( 1-->4)- lactone is a measure of the extent and speed of its conversion into the aldono-5-lactones in aqueous solution.
Abstract: 1. A method was devised for the preparation of (1-->5)-lactones from pyranose sugars and uronic acids by platinum-catalysed oxidation with gaseous oxygen in aqueous solution at acid pH. It was applied to mannose, N-acetylglucosamine, N-acetylgalactosamine, glucuronic acid, galacturonic acid, galactose, l-arabinose and d-fucose. 2. Only the first three yielded products that could be obtained in the solid state without decomposition. In every case, however, the oxidation product in aqueous solution behaved as the aldono-(1-->5)-lactone, and was more inhibitory towards the appropriate glycosidases than any aldonolactone preparation hitherto examined. 3. The stabilities of the oxidation products were studied, and their interconversion with the (1-->4)-lactones was demonstrated. Ring-opening does not appear to be mandatory for this isomeric change, which in some instances is very rapid. 4. To explain all the inhibitory effects observed with aldonolactones on glycosidases of corresponding configuration, it is tentatively postulated that inhibition may be due entirely to the (1-->5)-lactone, and that any inhibitory effect seen with the (1-->4)-lactone is a measure of the extent and speed of its conversion into the (1-->5)-lactone in aqueous solution.

62 citations

Journal ArticleDOI
TL;DR: The data suggest that a competent reductive half-reaction requires a side chain at position 169 that is able to form an H-bond within the ES complex, and that the precise position and geometry of the Thr169 side chain are required for intermediate stabilization.

61 citations

Journal ArticleDOI
TL;DR: It was shown that CuCl/CuCl2/tris(2-dimethylaminoethyl)amine (Me6TREN) catalytic system with an optimized ratio of Cu(I)/Cu(II) produced glycopolymer with high molecular weight and relatively narrow molecular weight distribution, which showed a proportional relationship with the molecular weight of free polymer generated in the solution.

61 citations

Journal ArticleDOI
TL;DR: In developing MM4 to reproduce these data, it was necessary to have good energies for simple alcohols and ethers, together with an adequate treatment of hydrogen bonding, and then to include the anomeric effect, and the ethylene glycol type system, as was previously recognized.
Abstract: Ab initio calculations [B3LYP/6-311++G(2d,2p)] have been carried out on 84 conformations of 12 different sugars (hexoses), in both pyranose and furanose forms, with the idea of generating a data base for carbohydrate structural energies that may be used for developing the predictive value of molecular mechanics calculations for carbohydrates. The average value for the apparent gas phase anomeric effect for a series of 31 pairs of pyranose conformations was found to be 1.83 kcal/mol (vs. 2.67 kcal/mol with a smaller basis set used in earlier calculations). In developing MM4 to reproduce these data, it was necessary first to have good energies for simple alcohols and ethers, together with an adequate treatment of hydrogen bonding, and then to include the anomeric effect, and the ethylene glycol type system, as was previously recognized. It was also found that the so-called delta-2 effect, long recognized in carbohydrates, must be explicitly included, in order to obtain acceptable results. When a force field that included all of these items as developed from the small molecules based on the MM4 hydrocarbon force field was applied without any parameter adjustment to the set of hexopyranose and furanose conformations mentioned earlier, the Eβ − Eα was found to have an average value of 1.88 kcal/mol, versus 1.74 for the quantum calculations. The signed average and RMS deviations of the MM4 from the QM results were +0.15 and 0.87 kcal/mol. © 2003 Wiley Periodicals, Inc. J Comput Chem 24: 1504–1513, 2003

61 citations


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Performance
Metrics
No. of papers in the topic in previous years
YearPapers
202317
202228
202118
202027
201926
201819