Solution chain conformation

The unusual properties of xanthan undoubtedly result from its stmctural rigidity, which in turn is a consequence of its Linear, ceUulosic backbone that is stiffened and shielded by the trisaccharide side chains. The conformation of xanthan in solution is a matter of debate. It does appear that the conformation changes with conditions. 

Small angle X-ray scattering Rg, chain contour length, L solution conformation and flexibility If M is also known, can provide mass per unit length Ml [5]... 

Polyisocyanates have attracted much attention owing to their liquid crystalline properties, stiff-chain solution characteristics, and induced optical activities associated with helical chain conformation (Scheme 8). Pattern and Novak [39]... 

Varadan, R., Assealg, M., Haririnia, A., Raasi, S., Pickart, C., and Fushman, D. Solution conformation of Lys63-linked di-ubiquitin chain provides clues to functional diversity of polyubiquitin signaling, J Biol Chem, 2003, 8, 7055-63. 

The other three X-ray structures show the expected lamp-like geometry. While for 3e in solution conformers are known (see Sect. 3.2.) and the chains X and Y may have varying orientations, such flexibilities are not existent in the concave 1,10-phenanthroline 21a and in the concave benzoic acid 38a. Here the X-ray structure should be much closer to the conformations in solution. 

Methods used to obtain conformational information and establish secondary, tertiary, and quaternary structures involve electron microscopy, x-ray diffraction, refractive index, nuclear magnetic resonance, infrared radiation, optical rotation, and anisotropy, as well as a variety of rheological procedures and molecular weight measurements. Extrapolation of solid state conformations to likely solution conformations has also helped. The general principles of macromolecules in solution has been reviewed by Morawetz (17), and investigative methods are discussed by Bovey (18). Several workers have recently reexamined the conformations of the backbone chain of xylans (19, 20, 21). Evidence seems to favor a left-handed chain chirality with the chains entwined perhaps in a two fold screw axis. Solution conformations are more disordered than those in crystallites (22). However, even with the disorder-... 

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