Polysaccharides conformation analysis

On the other hand, the method examines the rotations of contiguous residues about the glycosidic bonds, for example, C-l-O and O-C-4 in a (1 —> 4)-linked polysaccharide. This method scans the entire conformational space available to a polymer. The analysis can thus proceed either with a regular, helical structure, or a random conformation. The method has been used quite extensively in the conformational analysis of polysaccharides.9 26 The steric... 

N 137 "Conformational Analysis of Polysaccharides, Part II. Alternating Copolymers of the Agar-Carrageenan-Chondroitin type by Model Building in the... 

N 142 "Conformational Analysis of Polysaccharides. Part V. The Characterization of Linkage Conformations (Chain Conformations) by Optical Rotation at a... 

Further developments in NMR were presented in Sydney (1980) on high-resolution NMR by J. F. G. Vliegenthart, and on two-dimensional NMR by L. D. Hall. More applications of conformational analysis were discussed by K. Bock (Vancouver 1982) on the conformations of oligosaccharides, by H. J. Jennings (Utrecht 1984), on the conformations of some polysaccharides, by I. Tvaroska (Stockholm 1988), on computational methods for determining conformations, and by Y. Kishi (Paris 1992) on the conformations of C-glycosyl compounds. 

Rees DA (1970) Conformational analysis of polysaccharides. Part V. The characterization of linkage conformations (chain conformations) by optical rotation at a single wavelength. Evidence for a distortion of cyclohexaamylose in aqueous solution. Optical rotation and the amylose conformation. J Chem Soc B 877-884... 

Conformational analysis of BS I by c.d. spectroscopy indicated that the protein contained 30-40% of /3 structure in its native conformation.623 The c.d. spectrum was relatively insensitive to alteration in pH, removal of bound metal, and addition of methyl a-D-galactopyranoside. However, addition of dodecyl sodium sulfate or 2,2,2-trifluoroethanol resulted in the formation of some a-helical structure, and was accompanied by the loss of polysaccharide-precipitating capacity. Urea (8 M) irreversibly denatured the lectin. 

This article is the third in the current series on the bibliography of crystal structures of polysaccharides.1,2 In the past decade, many advances in the methods for building theoretical models were witnessed, not only for the conformational analysis of isolated chains, but also for the subsequent or simultaneous packing of the chains in the crystallographic lattice. Many complex polysaccharides, having disaccharide to hexasaccharide repeating units, are now being studied. 

Current methods take root in the early 1960s, when the conformational analysis of macromolecules became of general interest [29-30]. Anderson et al. [31] used model building and X-ray diffraction studies to determine the double helical structures of polysaccharides using crystalline structure data as an initial set of coordinates followed by computational sampling of new structures by rotation around selected covalent bonds. The details of these so-called hard-sphere calculations are described in Rees and Skerrett [32] and Rees and Smith [33]. This approach was also applied to carbohydrate conformations in the analysis of bacteria and polysaccharidic structures and linkages [34-35]. 

C. Hoog, A. Rotondo, B. D. Johnston, and B. M. Pinto, Synthesis and conformational analysis of a pentasaccharide corresponding to the cell-wall polysaccharide of the Group A Streptococcus, Carbohydr. Res., 337 (2002) 2023-2036. 

L. A. Mulard, M.-J. Clement, A. Imberty, and M. Delepierre, Synthesis of ligands related to the O-specific polysaccharides of Shigella flexneri serotype 2a and Shigella flexneri serotype 5a. Part 7. Convergent synthesis, NMR and conformational analysis of tetra- and pentasaccharide haptens of the Shigella flexneri serotype 5a O-specific polysaccharide, Eur. J. Org. Chem, (2002) 2486-2498. 

The non-covalent interactions of polysaccharides with themselves are covered, as the regular, repeating structures that result (helices, ribbons and so forth) can be rationalised by the normal methods of conformational analysis. 

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