Volume polysaccharides

G. O. Aspinall. The Polysaccharides, Volume 1. 1982 Charis Ghelis and Jeannine Yon. Protein Folding. 1982... 

Five articles on polysaccharide helices solved prior to 1979 have appeared in the volumes published between 1967 and 1982.2-6 The first was a review on X-ray fiber diffraction and its application to cellulose, chitin, amylose, and related structures, and the rest were bibliographic accounts. Since then, X-ray structures of several new polysaccharides composed of simple to complex repeating units have been successfully determined, thanks to technological advances in fiber-diffraction techniques, the availability of fast and powerful computers, and the development of sophisticated software. Also, some old models have been either re-... 

X-Ray diffraction analysis of oriented polysaccharide fibers has had a long history. Marchessault and Sarko discussed this topic in Volume 22 of Advances, and a series of articles by Sundararajan and Marchessault in Volumes 33, 35, 36, and 40 surveyed ongoing developments. The comprehensive account presented here by Chandrasekaran (West Lafayette, Indiana) deals with some 50 polysaccharides, constituting a wide range of structural types, where accurate data and reliable interpretations are available. The regular helical structures of the polysaccharide chains, and associated cations and ordered water molecules, are presented in each instance as stereo drawings and discussed in relation to observed functional properties of the polymers. 

Interactions with xanthan were investigated for some GAX fractions of wheat bran [109]. Whereas, for lowly substituted GaMs a synergy in viscosity was observed at low total polymer concentrations, yielding a maximum of the relative viscosity at nearly equal proportions of both polysaccharides [124], the xanthan/xylan mixtures at the same experimental conditions showed no synergy. The observed decrease in the relative viscosity values upon addition of the xylan indicates that a certain interaction with xanthan takes place, but that it leads to a contraction in the hydrodynamic volume. The authors suggested that structural and conformational differences between GaM and GAX might be the reason for this observation. 

Po and rio are the densities and viscosities of the solvent, P2o,w and rj2o,w the corresponding values at 20.0 °C in water, v is the partial specific volume, which for neutral polysaccharides can often be reasonably estimated from the carbohydrate content [31] and takes on values between 0.5-0.7 ml/g for... 

Combination of the Perrin function, p often referred as the frictional ratio due to shape with the frictional ratio (f/fo) enables the degree of expansion of the molecule (vh/ w ) to be estimated, where Vh, (cw / g) is the volume of the swollen molecule (Polysaccharide or protein + associated solvent) per unit mass of polysaccharide and v is the partial specific volume (essentially the anhydrous molecule) ... 

The total polysaccharide preparations from wine, apple and tomato juices were analysed in our HPSEC system. The obtained profiles (Figure 2) were all characterized by the presence of a main sharp peak eluted at the same elution volume (18.2 to 18.6 min) as a previously purified wine RG-II [20]. 

O Neill, M., Albersheim, P., and DarviU, A. (1990) The pectic polysaccharides of primary cell walls. In Methods in Plant Biochemistry, Volume 2, edited by P.M. Dey, pp. 415-441. Academic Press, London. 

Chromatorapf c methods For gel filtration of polysaccharide fraction PI, a Sephacryl S-300 chromatographyc column (1,1 X 46,7 cm) was calibrated with standard dextrans (molecular mass range 266, 72, 40, and 17 KDa Sigma Chemicals), and the void volume determined with blue dextran. Polysaccharide sample (0.5 mL 2 mg/mL) was applied and eluted with 50 mM NaOH, fractions 1 mL being collected and carbohydrate absorbance (phenol-H2S04) being monitored. 

Xylose-rich pectic polysaccharide was extracted from defatted and protein-free cell wall preparation (5) using HCl solution (pH 1.6) at 85° C for 4 h. The extract was adjusted to pH 5.0 with ammonia, concentrated on a rotary evaporator under reduced pressure at 40°C, and precipitated with 5 volumes of 96% ethanol. After washing twice with 80% ethanol and drying in an air circulated oven at 40°C for 2 h, the pellet was ledissolved with distilled water and then precipitated with 4 vols 96% ethanol. Before the pellet was gently ground, the precipitated pellet was washed twice with 70% ethanol and dried at 40 ° in an air circulated oven for 16 h. The resultant white powder was labelled "xylose-rich pectic polysaccharide" and stored in a refrigerator. 

Growth of the Helianthus annuus 1805 cell suspension and biosynthesis of extracellular polysaccharides. A particular characteristic of plant cell suspensions is the requirement for a high inoculation density in order to initiate growth. This is due to one of their special features in order that their growth be initiated when transferred into the new medium, they need certmn growth factors which are released and secreted into the medium by the cells themselves. Consequently, to ensure the growth of plant cell suspensions, a certain volume (in which plant cells have to be present at above certain densities) has to be used to import the necessary quantity of these substances (17). 

Isolation and characteristics of the polysaccharides. It is known (1,3,4,6) that the polysaccharides from a culture medium can be precipitated by adding different volumes of ethanol (1 2, 1 3). Our experiments with precipitation with ethanol at a ratio of 1 3 led to the isolation of crude polysaccharides from the culture medium (Sample 1). 

Volume 3 Modifications and Applications of Industrial Polysaccharides (Yalpani, Editor)... 

Exudate collection in trap solutions usually requires subsequent concentration steps (vacuum evaporation, lyophilization) due to the low concentration of exudate compounds. Depending on the composition of the trap solution, the reduction of sample volume can lead to high salt concentrations, which may interfere with subsequent analysis or may even cause irreversible precipitation of certain exudate compounds (e.g., Ca-citrate, Ca-oxalate, proteins). Therefore, if possible, removal of interfering salts by use of ion exchange resins prior to sample concentration is recommended. Alternatively, solid-phase extraction techniques may be employed for enrichment of exudate compounds from the diluted trap solution (11,22). High-molecular-weight compounds may be concentrated by precipitation with organic solvents [methanol, ethanol, acetone 80% (v/v) for polysaccharides and proteins] or acidification [trichloroacetic acid 10% (w/v), per-... 

Acid hydrolysis of the polysaccharide portion of wood will release lignin but also causes major condensation reactions in the product(2l). These reactions can be minimized by using 41 wt. percent hydrochloric acid in place of other mineral acids but some condensation reactions still occur(22). This is not an effective method by which to obtain unaltered lignin. On the other hand, lignin can be solvent extracted from wood at temperature of 175°C using solvent mixtures such as 50/50 by volume water/1,4-dioxacyclohexane(23) Changes in lignin under these conditions appear to be minor. 

A substance that fulfills these criteria is inulin, a polysaccharide found in plants. Inulin is administered intravenously to a patient at a rate that results in a constant plasma concentration over the course of at least 1 h. The urine is collected and its volume and concentration of inulin are measured. 

Volume 203. Molecular Design and Modeling Concepts and Applications (Part B Antibodies and Antigens, Nucleic Acids, Polysaccharides, and Drugs) Edited fey John J. Langone... 

The ethylene glycol-containing silica precursor has been combined, as mentioned above, with most commercially important polysaccharides and two proteins listed in Table 3.1. In spite of the wide variety of their nature, structure and properties, the jellification processes on addition of THEOS to solutions of all of these biopolymers (Scheme 3.2) had a common feature, that is the formation of monolithic nanocomposite materials, proceeding without phase separation and precipitation. The syner-esis mentioned in a number of cases in Table 3.1 was not more than 10 vol.%. It is worthwhile to compare it with common sol-gel processes. For example, the volume shrinkage of gels fabricated with the help of TEOS and diglyceryl silane was 70 and 53 %, respectively [138,141]. 

The pneumococcal polysaccharides were treated in a previous Volume of this Series.1 The immunological properties of these polysaccharides have been well studied,2 thanks to extensive work by Heid-... 

---