Complex Polysaccharides

The rharonogalacturonans are associated physically and covalendy with associated polysaccharides. Several less common sugars are also covalently Unked to the polysaccharide complex. 

Fig. 12 Mitogenic (Slmit) and comitogenic (SIcomit) activities of the acemannan isolated from the filet (HFl), the polysaccharide complex (SLl) of the skin of aloe vera, and the commercial fungal immunomodulator Zymosan (Zym) [207]...

Various zirconium compounds are used as delayed crosslinkers, (see Table 17-12). The initially formed complexes with low-molecular-weight compounds are exchanged with intermolecular polysaccharide complexes, which cause delayed crosslinking. 

Chemical analyses of capsular material from a number of bacteria show wide differences in composition. For this reason it is impossible to make statements which apply to all bacteria. In some organisms the capsular material appears to be a glycoprotein in others, a protein-polysaccharide complex in still others, a polysaccharide framework with the spaces filled in by a larger amount of glutamyl polypeptide. 

Attachment There is a high specificity in the interaction between virus and host. The most common basis for host specificity involves the attachment process. The virus particle itself has one or more proteins on the outside which interact with specific cell surface components called receptors. The receptors on the cell surface are normal surface components of the host, such as proteins, polysaccharides, or lipoprotein-polysaccharide complexes, to which the virus particle attaches. In the absence of the receptor site, the virus cannot adsorb, and hence cannot infect. If the receptor site is altered, the host may become resistant to virus infection. However, mutants of the virus can also arise which are able to adsorb to resistant hosts. 

V. Naturally Occurring Polysaccharide Complexes of Interest in Connection... 

The finding that, when the protein-polysaccharide complex (mainly chondroitin 4-sulfate) from pig rib-cartilage was treated with 0.2 M potassium hydroxide for 20 hours at 4°, only about 80% of the carbohydrate moieties were removed by /3-elimination, was interpreted as... 

B) protein-polysaccharide complex with amphiphilic compounds... 

Turgeon, S.L., Schmitt, C., Sanchez, C. (2007). Protein-polysaccharide complexes and coacervates. Current Opinion in Colloid and Interface Science, 12, 166-178. 

Electrostatic and non-electrostatic biopolymer complexes can also be used as effective steric stabilizers of double (multiple) emulsions. In this type of emulsion, the droplets of one liquid are dispersed within larger droplets of a second immiscible liquid (the dispersion medium for the smaller droplets of the first liquid). In practice, it is found that the so-called direct water-in-oil-in-water (W/O/W) double emulsions are more common than inverse oil-in-water-in-oil (O/W/O) emulsions (Grigoriev and Miller, 2009). In a specific example, some W/O/W double emulsions with polyglycerol polyricinoleate (PGPR) as the primary emulsifier and WPI-polysaccharide complexes as the secondary emulsifying agent were found to be efficient storage carriers for sustained release of entrapped vitamin Bi (Benichou et al., 2002). 

Schmitt, C., Sanchez, C., Sobry-Banon, S., Hardy, J. (1998). Structure and technofunctional properties of protein-polysaccharide complexes. Critical Reviews in Food Science and Nutrition, 38, 689-753. 

Dickinson, E., Galazka, V.B. (1992). Emulsion stabilization by protein-polysaccharide complexes. In Phillips, G.O., Wedlock, D.J., Williams, P.A. (Eds). Gums and Stabilisers for the Food Industry 6, Oxford IRL Press, pp. 351-362. 

At the mixing ratio where coacervation is maximized, the protein-polysaccharide complexes are electrically neutral. 

The expected greater size of protein-polysaccharide complexes can reduce the diffusion rate of the adsorbing species towards the interface. This effect is especially important for small monomeric proteins. In addition, Ganzevles and co-workers (2006) have suggested that the diffusion of protein in the complexes may not solely be responsible for the slow surface tension decay. Rather, the gradual dissociation (and subsequent adsorption) of protein from complexes, when they are in close proximity to the interface, could also contribute to the behaviour. 

Table 7.2 Effect of the presence of an anionic polysaccharide on the measured zeta potential (Q of emulsion droplets stabilized by proteins under experimental conditions corresponding to protein-polysaccharide complexation. In all cases the complexes were formed in the bulk aqueous medium before emulsification.

Therefore, two contributory factors may provide an explanation for more effective electrostatic / steric stabilization of the so-called mixed emulsions in comparison with the sequentially assembled biopolymer interfaces of the bilayer emulsions firstly, a greater hydrophilicity of the adsorbed protein-polysaccharide complexes, caused by the larger net negative charge, and, secondly, a more bulky architecture of the normal complexes as compared to the interface complexes. 

In general, surface activity behaviour in food colloids is dominated by the proteins and the low-molecular-weight surfactants. The competition between proteins and surfactants determines the composition and properties of adsorbed layers at oil-water and air-water interfaces. In the case of mixtures of proteins with non-surface-active polysaccharides, the resulting surface-activity is usually attributed to the adsorption of protein-polysaccharide complexes. By understanding relationships between the protein-protein, protein-surfactant and protein-polysaccharide interactions and the properties of the resulting adsorbed layers, we can aim to... 

Protein-polysaccharide complexation affects the surface viscoelastic properties of the protein interfacial layer. Surface shear rheology is especially sensitive to the strength of the interfacial protein-polysaccharide interactions. Experimental data on BSA+ dextran sulfate (Dickinson and Galazka, 1992), asi-casein + high-methoxy pectin (Dickinson et al., 1998), p-lactoglobulin + low-methoxy pectin (Ganzevles et al., 2006), and p-lactoglobulin + acacia gum (Schmitt et al., 2005) have all demon-... 

In another set of studies, it has been reported that the in vitro digestibility of lipid droplets by pancreatic lipase is significantly affected by emulsifier type (Mun et al, 2006, 2007 Park et al., 2007). Intuitively, one might expect that a thick dense layer of strongly bound protein-polysaccharide complex at the oil-water interface would reduce considerably the in vivo accessibility of lipases, and hence would reduce the rate of human metabolism of fats. Establishment of the validity of this hypothesis must still await consolidation of a substantial body of detailed results from independent systematic studies on a broad range of mixed biopolymer systems. 

Gurov, A.N., Nuss, P.V. (1986). Protein-polysaccharide complexes as surfactants. Nah-rung, 30, 349-353. 

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