Polysaccharides, types

Composition and Methods of Manufacture. The vaccine consists of a mixture of purified capsular polysaccharides from 23 pneumococcal types that are responsible for over 90% of the serious pneumococcal disease in the world (47,48). Each of the polysaccharide types is produced separately and treated to remove impurities. The latter is commonly achieved by alcohol fractionation, centrifugation, treatment with cationic detergents, proteolytic en2ymes, nucleases or activated charcoal, diafiltration, and lyophili2ation (49,50). The vaccine contains 25 micrograms of each of the types of polysaccharide and a preservative such as phenol or thimerosal. 

Based on the current stage of knowledge, hemicelluloses can be divided into four general classes of structurally different cell-wall polysaccharide types, i.e.,... 

Molecular Structure. Most starches consist of a mixture of two polysaccharide types amylose, an essentially linear polymer, and amylopectin, a highly branched polymer. The relative amounts of these starch fractions in a particular starch are a major factor in determining the properties of that starch. 

Girod, M., Chankvetadze, B., and Blaschke, G. (2000) Enantioseparations in non-aqueous capillary electrochromatography using polysaccharide type chiral stationary phases, J. Chromatogr. A 887, 439-455. 

Polysaccharide type Micro-organism Component sugars Gal Glc Man Other substituents References... 

K. Tachibana and A. Ohnishi, Reversed-phase hquid chromatographic separation of enantiomers on polysaccharide type chiral stationary phase, J. Chromatogr. A 906 (2001), 127-154. 

The capsular polysaccharide of the pathogenic yeast Cryptococcus neoformans (Torula histolytica) is serologically active, and there is evidence that it is responsible for the antigenic reaction in man. The capsule is generally quite thick, and can be larger in diameter than the cell body. Three polysaccharide types, namely. A, B, and C, have been differentiated on the basis of precipitin, agglutination, and quellung reactions. ... 

The starch granule contains two polysaccharide types amylose, which is a linear polymer, and amylopectin, which is a branched polymer. Amylose is composed of linear chains of about 800 to 22,000 a-D-glucopyranosyl units in (a-1,4) linkage... 

Benaissa-Trouw B, Lefeber DJ, Kamerling JP, Vliegenthart JF, Kraaijeveld K, Snippe H. Synthetic polysaccharide type 3-related di-, tri-, and tetrasaccharide-CRM(197) conjugates induce protection against Streptococcus pneumoniae type 3 in mice. Infect Immun. 2001 69 4698-4701. 

A) Macromolecular SOs They can be divided (a) into those consisting of the same repeat units or monomers (homopolymer) comprising the naturally occurring polysaccharide type SOs as well as synthetic polymeric type SOs (including polymethacrylate and imprinted polymer type SOs), and (b) into those made up of different repetitive units or monomers like the proteins. 

Polysaccharide type CSPs as well as most synthetic polymeric type CSPs have no ionic interaction sites and thus are primarily operated in the normal-phase mode. Proteins, in contrast, have several (positively and negatively) charged adsorption sites for strong ionic interactions, which have to be balanced by buffered mobile phases. The system must take into account that denaturation of the proteins must not occur, which limits the amounts of organic mridifiers that can be used as part of the aqueous mobile phase. 

ENANTIOSEPARATION OF PHARMACELTICALLY RELEVANT CHIRAL COMPOLNUS USING POLYSACCHARIDE TYPE CSPs... 

For all the polysaccharide type CSPs, their primary mode of operation, panicularly for preparative separations, is the normal-phase mcxle. Usually, w-heptane or n-hexane-isopropanol, resp. ethanol, mixtures are employed as mobile phases. For the separation of acids, small quantities of acids, e.g. trifluoroacetatic acid, are added to the mobile phase [147], The tailing of basic SAs on the other hand can be reduced with addi-... 

One considerable disadvantage of coated polysaccharide type CSPs, however, is the high solubility of the SO in many organic solvents, e.g. chloroform, ethylacetate, and tetrahydrofuran, restricting the choice of mobile phases that can be used. Accordingly, inflexibility in the optimization of separations and enantioselectivity is a considerable drawback this counts in particular for preparative separations, where often the solubility of the SAs in the mobile phase is limited and thus loadability and finally the productivity rate is reduced. 

Enantioseparations in SEC have been reported for several CSPs. including native and derivatized cyclodextrin-based CSPs [427-432. Pirkle-concept CSPs [77,336-338,347,348,363,365,433,434], polysaccharide type CSPs [137.435-438], macrocyclic antibiotic type CSPs [436], and others. 

From the list in Table 3.9, cellulose and amylose-based phases are by far the most often used in preparative and, especially, SMB applications. These adsorbents offer good productivities because of their high loadabilities (Fig. 3.22). In addition, the four most commonly used CSP of this type separate a broad range of different race-mates. The major problem of these adsorbents is their limited solvent stability, especially towards medium-polar solvents such as acetone, ethyl acetate or dioxane. In the past their use in conjunction with aqueous mobile phases was not recommended by the manufacturer as well. However, this limitation was successfully overcome by recent studies, in which amylose- and cellulose-based CSPs are transferred to the reversed phase (RP) mode with aqueous mobile phases. The first results for the use of polysaccharide-type phases with aqueous solvents were reported by Ishikawa and Shibata (1993) and McCarthy (1994). The stability of the adsorbent after switching to RP conditions has been reported by Kummer et al. (1996) to be at least 11 months and by Ning (1998) to be 3 years. No peak deviation is observed after switching to RP mode. Novel developments have led to polysaccharide-based adsorbents dedicated to use with nearly all organic solvents (Cox and Amoss, 2004). 

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