Polysaccharides display

The identicalness of the ionization sites in a linear polyelectrolyte (Tanford, 1961) stimulated the interest of Walter and Jacon (1994) in a possible relationship between Kz and M of ionic polysaccharides displaying the characteristic titration curve of a weak, monobasic acid. Without any theoretical assumption, Eq. (S.4) was derived from simple algebra by combining elementary principles of the dissociation theory of weak acids with polymer segment theory ... 

It is known that these polysaccharides display "remarkable surface adsorptive capacity both for organic and inorganic substances. It is therefore possible that these traces of nitrogen and phosphorus are due to strong adsorption between the polysaccharide and small amounts of protein or nucleic acid (or nucleic acid fragments). Such a system is resistant to the usual methods of fractionation, but a separation by electrophoretic means has been claimed. 

Under the electron microscope the uranium complexes of the formazans of ozonized polysaccharides display a distinct shading effect, the polysaccharides showing a deep black color. On this basis it is to be hoped that a new electron microscopic method will soon be elaborated (6),... 

The literature indicates that the proton NMR spectra of polysaccharides display severe overlap of signals in the chemical shift region of 3.5-5.5 ppm and it is difficult to assign them using ID H NMR spectrum alone [90,127]. This difficulty can be overcome by the fact that polysaccharides display a wide range of chemical shifts when compared to their H shifts. Carbon chemical shifts of polysaccharides appear in the range of 60-110 ppm. 

Sage polysaccharides displayed immunomodulatory activity in the in vitro comito-genic thymocyte test3 ... 

The "dry process" relies on the thermoplastic behavior that some proteins and polysaccharides display at low moisture levels in compression molding and extrusion (Hemandez-lzquierdo and Krochta, 2008). 

Interestingly, polysaccharide bilayers are considerably thicker than polypeptide ones. To understand these differences, it has to be taken into account that the relative layer thickness depends on several factors, mainly charge density, hydrophilicity, M, residue size, etc. On the one hand, polysaccharides display higher chaige densities, and tend to adopt a stretched conformation to minimize the repulsion between charges, which would lead to thinner layers. On the other hand, they present increased hydrophilicity and consequently adsorb more water, which would result in an increase of the thickness. Furthermore, a rise in the PE M and chain length typically causes an increase in the amount of material adsorbed. Overall, it is found that the adsorption of the polysaeeharides results in the formation of thicker bilayers. 

Among the spectroscopic methods applicable to polysaccharides, u.v. spectrophotometry is of little value for characterizing heparin, whose main, electronic chromophore (the C02 group) displays a band at 220 nm, that is, in a region where all glycosaminoglycans absorb (also through their N-acetyl chromophores), and where minor proportions of unsaturated or aromatic contaminants cause serious interference.77 With pure heparin preparations, the carboxylate chromophore is most useful for chiroptical measurements, and a semi-quantitative evaluation of the extent of N-acetylation of 2-amino-2-deoxy-D-glucose residues is also possible.78... 

Kennedy et al. [57] have described the use of an intelligent chiral resolution system using a rapid screening of conditions on polysaccharide CSP, aiming to transfer the separation to preparative LC afterward. For the analytical part of the strategy, lO-pm particles were used for the preparative section, the particles had a 20-ttm diameter. The screening performs 11 experiments on analytical columns, which are displayed in Table 3.3. Chiralpak AD, Chiralcel OD, Chiralcel OJ, and Chiralpak AS are the considered stationary phases, and they are analyzed either in POSC or NPLC mode. The... 

Fig. 7 A model of the cell-wall polysaccharide (CWPS) of group A Streptococcus, looking down the barrel of the helix. The core of the helix is composed of a-L-rhamnose residnes with the 8-d-G1cNAc moieties displayed on the periphery. Reprodnced with permission from [99]. 2004 Elsevier Science...

MAbs directed against the C. neoformans polysaccharide are closely related, and some differ only in a few amino acid residues [142,143]. This fine specificity is related to their protective efficacy. A highly protective IgGl mAh was used to screen phage-displayed peptide libraries, and several binding peptide sequences were identified [144]. The dodecapeptide GLQYTPSWMLVG bound to the mAh with a Kd of 295 nM, measured by surface plasmon resonance (SPR) and inhibited binding of the mAh to the polysaccharide. The dodecapeptide was able to induce only a weak antipolysaccharide antibody response [145]. 

In the course of screening N9/cationic polymer formulations, an important observation was made. Hydrophobe modified cationic polysaccharides [33] displayed unique sperm impedance, but not spermicidal, properties. By contrast, the related non-hydrophobe modified material was devoid of that effect. It is important to state that hydrophobe incorporation into water soluble polymers, at the desired level for optimum efficacy, is complex. Chemical efficiency can be low in the derivatized polymer and solubility characteristics change dramatically. Of the various hydrophobes evaluated in these studies, the —C12H25 hydrophobe was preferred. 

Emphasis in the initial phase of our work was placed on sulfated polysaccharides that are antiviral. Not only were the desired rheological properties and long-term stability achieved in DCE formulations, the activity of the dextran sulfate or N9 were not compromised. DCE formulations containing DS display strong anti-HIV activity in vitro in comparison with negative (not shown) and positive controls (Figure 2). This is an important first step in the screening process towards clinical effectiveness. 

We were successful earlier in achieving anioiuc/cationic complexes with glycosaminoglycans, e.g., hyaluronic acid/cationic polysaccharide compositions [44], now used in personal care applications. Those compositions are substantive, stable and user-friendly. Unfortunately, despite the highly anionic nature of hyaluronic acid (and other glycosaminoglycans), these materials do not block viral infections [39]. Furthermore, as shown by the in vivo rabbit irritation studies, such compositions displayed minimal irritation [13]. 

A second example [IJ) is that of the anomeric spectral region of dextran B-742 fraction S, a polysaccharide for which per-methylation data indicate Structure 2, when n=0. This is an unusual polymer, as every backbone residue is 3-0-substituted. It is fortunate that this polymer exists, as the dextrans branching through 3,6-di-O-substituted residues present a problem in the anomeric spectral region, displaying only a single branching anomeric resonance in addition to the linear dextran resonance. 

---