Rigidity, polysaccharides

In the course of studies on the physicochemical properties of natural polymers in aqueous solution, attention has been drawn to pectic acid, i.e. poly (a-D)galacturonic acid as a potential model of a rigid polysaccharide. 

Singh s easy approachability model [60-65] explains the superiority of grafted polysaccharides over other types of flocculants. This model states that the dangling branches of polyacrylamide or cationic moiety have easy approach-ability when they are grafted onto the rigid polysaccharide backbone. 

K. Kurita, M. Kamiya, S.-l. Nishimura, Solubilization of a rigid polysaccharide controlled partial N-acetylation of chitosan to develop solubility, Carbohydr. Polym. 16 (1991) 83-92. 

Nishimura, S., Kohgo, O., Kurita, K., and Kuzuhara, H. 1991. Chemospecific manipulations of a rigid polysaccharide Syntheses of novel chitosan derivatives with excellent solubility in common organic solvents by regioselective chemical modifications. Macromolecules 24 4745-4748. 

Ferretti, R., Stoll, S., Zhang, J. and Buffle, J. (2003). Flocculation of hematite particles by a comparatively large rigid polysaccharide schizophyllan. J. Colloid Interface ScL, 266, 328-338. 

In a model flavour-release system, 2-octanone could be released from BSA-pectin complexes by a shift in pH [113]. This was due to BSA imfolding on the oppositely charged, rigid polysaccharide matrix at a pH below the isoelectric point of BSA. DSC was used to examine the effect of flavour binding on the conformational stability of the protein. 

X>, the experimental values obtained with rigid polysaccharides are higher than the theoretical ones. 

Cell wall Peptidoglycan a rigid framework of polysaccharide cross-linked by short peptide chains. Some bacteria possess a lipopolysaccharide- and protein-rich outer membrane. Mechanical support, shape, and protection against swelling in hypotonic media. The cell wall is a porous nonselective barrier that allows most small molecules to pass. 

A polysaccharide such as xanthan gum is a chain of sugars. Some familiar polysaccharides are starch and cellulose. The backbone of xanthan gum is similar to cellulose, but the trisaccharide side chains of mannose and glucuronic acid make the molecule rigid, and allow it to form a right-handed helix. These features make it interact with... 

The sedimentation coefficient provides a useful indicator of polysaccharide conformation and flexibility in solution, particiflarly if the dependence of on Mw is known [62]. There are two levels of approach (i) a general level in which we are delineating between overall conformation types (coil, rod, sphere) (ii) a more detailed representation where we are trying to specify particle aspect ratios in the case of rigid structures or persistence lengths for linear, flexible structures. 

Once a general conformation type or preliminary classification has been established it is possible to use sedimentation data to obtain more detailed information about polysaccharide conformation. For example, the low value of ks/[v 0 25 found for the bacterial polysaccharide xylinan has been considered to be due to asymmetry [115]. If we then assume a rigid structure the approximate theory of Rowe [36,37] can be applied in terms of a prolate ellipsoid of revolution to estimate the aspect ratio p L/d for a rod, where L is the rod length and d is its diameter) 80. 

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