Polysaccharide systems, structuring

Dea, I. C. M., McKinnon, A. A., and Rees, D. A. (1972). Tertiary and quaternary structure in aqueous polysaccharide systems which model cell wall cohesion reversible changes in conformation and association of agarose, carrageenan and galactomannans. J. Mol. Biol. 68 153-172. 

The viscosity obtained from the above equation in the linear region of a creep experiment can be used to extend the low-shear rate region of apparent viscosity versus shear rate data obtained in a flow experiment by about two decades (Giboreau et al., 1994 Rayment et al., 1998). The low shear rate region of about 10 -10 is often used for the characterization and differentiation of structures in polysaccharide systems through the use of stress controlled creep and non destructive oscillatory tests. The values of strain (y) from the creep experiment can be converted to shear rate from the expression y t) = y t)/t. 

Muhlethaler K (1969) Fine structure of natural polysaccharide systems. In Marchessault RH (ed), Proceedings of 6th cellulose conference. Wiley, New York, 57-67 Murphy RJ, Barnes HM and Dickinson DJ (2002) Vapor boron technology. In Enhancing the durability of lumber and engineered wood products. Forest Prodncts Society, Madison, Wisconsin, 251-6... 

A polysaccharide can be added as a component in a protein system to produce a protein-polysaccharide composite structure. Tolstoguzov (2003) reviewed the main function of protein and polysaccharide in protein-polysaccharide food formulation. Generally, polysaccharides have less surface activity in comparison to proteins. This inferiority is related to their low flexibility and monotonic repetition of the monomer units in the backbone. The low surface activity of polysaccharides results in their inability to form a primary adsorbed layer in the system. The nature of interactions between polysaccharides and adsorbed proteins, as well as their influence on colloid stability, can either stabilize or destabilize the emulsions. Attractive protein-polysaccharide interactions can enhance the emulsion stability by forming a thicker and stronger steric-stabilizing layer. In contrast, the attractive interactions... 

Miihlenthaler, R., 1969. Fine structure of natural polysaccharide systems. J. Polym. Sci. C 28, 305-316. 

In general ordered conformations are promoted by favourable non-covalent interactions, inflexible secondary structure, and efficiency of packing, and inhibited by loss of conformational entropy, energy of hydration, intermolecular electrostatic repulsion, structural irregularities, and branching. The balance of these opposing drives is often delicate, and may be tipped by relatively small perturbations. For example, thermally induced order-disorder transitions, which may or may not be accompanied by a gel-sol transition, have been observed for a number of polysaccharide systems (8,13,14), and show the sharp temperature profile characteristic of a co-operative process. 

Antonov, Y. A., Grinberg, V. Y, Zhuravskaya, N. A. Tolstoguzov, V. B. (1980). Liquid 2-Phase Water-Protein-Polysaccharide Systems and their Processing into Structured Protein PtoAacts. Journal of Texture Studes, 11, 199-215. 

Cartesian and cylindrical polar atomic coordinates of the structural repeating unit of 31 polysaccharide helices are provided in Tables A1 to A31. Errors, if any, in the original publications have been corrected. The coordinates of hydrogen atoms are given in a majority of structures. If missing, they are not available in the references cited in Table I. Each table caption contains the structure number and polymer name assigned in Table I. Refer to Table II for its chemical repeating unit. Cartesian (x, y, z) and cylindrical (r, , z) coordinates are related by x r cost ), y = r sin<(> and z is the same in both systems. 

As mentioned in the introduction, various reviews over the last ten years show that many plants contain bioactive polysaccharides. Most of the plants studied were chosen due to their traditional use for different kinds of illnesses where the immune system could be involved. The following section will describe the pectic type polymers from the plants most studied for their structure, and activities related to the structure where possible. 

Black pepper contains several polysaccharides of which one shows a strong effect as an immune enhancer based on the fact that the polymer is an anti-complementary polysaccharide. The polysaccharide has an Mw of approx. 40 kD. It is composed basically of rhamnose, arabinose, galactose and galac-turonic acid, and shows a high binding capacity for the Yariv reagent. This indicates that the side chain of the polymer is of the arabinogalactan type II, which is a common structure for several polysaccharides with an effect on the complement system [70]. 

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