Polysaccharide charged

Jones, O.G., Lesmes, U., Dubin, P., McClements, D.J. Effect of polysaccharide charge on formation and properties of biopolymer nanoparticles created by heat treatment of jS-lactoglobulin-pectin complexes. Food Hydrocolloids 24, 374—383 (2010)... 

The behavior of polysaccharides is also critically influenced by the nature of the substituent groups bound to the individual monosaccharides. These substituents can be of natural origin or they may be synthesized and thus of seminatural quality. Whether they are natural or seminatural, the classification of polysaccharides falls into one of five categories, based primarily on the polysaccharide charge. These include anionic, cationic, nonionic, amphoteric, and hydrophobic. 

Cation (Section 1 2) Positively charged ion Cellobiose (Section 25 14) A disacchande in which two glu cose units are joined by a 3(1 4) linkage Cellobiose is oh tamed by the hydrolysis of cellulose Cellulose (Section 25 15) A polysaccharide in which thou sands of glucose units are joined by 3(1 4) linkages Center of symmetry (Section 7 3) A point in the center of a structure located so that a line drawn from it to any element of the structure when extended an equal distance in the op posite direction encounters an identical element Benzene for example has a center of symmetry Cham reaction (Section 4 17) Reaction mechanism m which a sequence of individual steps repeats itself many times usu ally because a reactive intermediate consumed m one step is regenerated m a subsequent step The halogenation of alkanes is a chain reaction proceeding via free radical intermediates... 

Most frequently, SEC with dextran-, pullulan-, or polystyrene calibration standards has been used to characterize the molecular properties of xylans. However, as for viscometric studies [108], a sufficient solvent ionic strength is a prerequisite for useful SEC measurements of charged polysaccharides, including glucuronoxylans [111-113]. An advantage of the SEC technique is that the presence of protein and phenolic components or oxidative changes can be detected by simultaneous ultraviolet (UV) detection. 

There are several techniques now at our disposal for obtaining this fundamental biophysical information about solutions of polysaccharides (Table 1 [2-7]), but as is well known these substances are by no means easy to characterise. These difficulties arise from their highly expanded nature in solution, their polydispersity, (not only with respect to their molecular weight but also for many with respect to composition), the large variety of conformation and in many cases their high charge and in some their ability to stick together [1,8]. All of these features can complicate considerably the interpretation of solution data. 

The 5 and 520,w obtained from Eqs. 1-3 will be apparent values because of the effects of solution non-ideality, deriving from co-exclusion and—for charged polysaccharides—polyelectrolyte effects [30]. To eUminate the effects of non-ideality it is necessary to measure either s or S2o,w for a range of different cell loading concentrations c, and perform an extrapolation to zero concentration. For polysaccharides this has been conventionally achieved from a plot of I/5 (or 1/S20,w) versus c [30] ... 

Winzor and coworkers have employed measurements of the Donnan distribution of small ions in dialysis equilibrium [14] to reinforce earlier evidence of charge-screening effects in polysaccharide anions [164,165]. These researchers used the absorption optical system of a Beckman XL-1 ultracentrifuge to monitor the distribution of ions in polysaccharide solutions... 

In a typical equilibrium dialysis study of charged polysaccharides an indicator ion, L (chromate), is included in the supporting electrolyte medium (phosphate buffer, pH 6.8, I 0.08) to allow assessment of the effective net charge of the polyanions via a modified form of Eq. 31, namely. 

Acquired resistance to polymyxins in E. coli occurs because of chromosomal mutations which cause incorporation of aminoethanol and aminocarabinose in lipo-polysaccharide (LPS) in place of phosphate groups. The altered LPS has a decreased ionic charge which results in lowered binding of polymyxin and thus an increase in resistance to this group of antibiotics. 

Production of the color involves centrifugal separation of the biomass, cell breakage, and extraction. Use of a salt solution rather than water as an extraction medium increases stability of the color during extraction. Methods for partial exclusion of the polysaccharide from the color extract in order to enhance resolubilization of the dried color were developed. These processes include either microfiltration or co-precipitation of the polysaccharide with an added positively charged polysaccha-... 

The polysaccharides present in the pectin-rich extract ChSS were fractionated, based on their charge density for further characterisation. The elution pattern of ChSS is shown in Figure 1, and it can be seen that the relative uronide content of the fractions increased with increasing salt concentration of the eluens. 

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