Polysaccharides distribution

Fig. 2. Low and high resolution maps of polysaccharides distribution in the Goniastrera skeleton (a) Polished surface of wall and septa (b) Low resolution X-ray fluorescence map higher concentrations of S-polysaccharides are visible in EMZ of wall and septa (c) High resolution X-ray fluorescence map in fibrous tissue. Evidence of the layered distribution of S-polysaccharides (d) Banding pattern within the mineral phase. Correspondence between mineral stepping growth and layered distribution of polysaccharides indicates that the two phases (organic and mineral) interplay at a submicrometre scale.

Alginic acid, also called algin or alginate, is an anionic polysaccharide distributed widely in the cell walls of brown algae. It binds with water to form a viscous gum. It absorbs water quickly and is capable of absorbing 200-300 times of water by its weight [142]. It is biocompatible and less toxic with relatively low cost and forms mild gelation by the addition of cations such as Na+ and Ca + [143]. 

Hydrogenated starch hydrolysates (HSH) is a term used to describe a range of products which do not contain sorbitol or maltitol as a primary component, ie, at least 50%. HSH symps contain a distribution of sorbitol, maltitol, and other hydrogenated oligo and polysaccharides. Symps containing maltitol at a level of at least 50% are referred to as Maltitol symps or Maltitol solutions. 

Cellulose is the most abundant of naturally occurring organic compounds for, as the chief constituent of the eell walls of higher plants, it comprises at least one-third of the vegetable matter of the world. The cellulose eontent of such vegetable matter varies from plant to plant. For example, oven-dried cotton contains about 90% cellulose, while an average wood has about 50%. The balance is composed of lignin, polysaccharides other than cellulose and minor amounts of resins, proteins and mineral matter. In spite of its wide distribution in nature, cellulose for chemical purposes is derived commerically from only two sources, cotton linters and wood pulp. 

Nonionic polysaccharides are one of the most simple substances to analyze by size exclusion chromatography because they seldom exhibit nonsize exclusion effects. Due to their wide molecular weight distribution, TSK-GEL PW columns are recommended for their analysis. 

Although carbohydrates/polysaccharides exist in such huge amounts, their industrial processing is expensive due to enormous quality fluctuations of succeeding raw material batches. The reason for these fluctuations is a high variability on the molecular level, particularly in the degree of polymerization distribution, in branching characteristics, and in complex interactive properties. 

Agarose gels have been used for more than two decades to separate polysaccharides (17-22). In particular, Sepharose CL 2B is widely used (6-8) to separate native starch, but continuously improved mechanical and chemical stability made all of the Sepharose CL gels perfect systems for the analysis of high molecular and broad distributed polysaccharides (23-28). 

A prehminary study of the use of larch AGs in aqueous two-phase systems [394] revealed that this polysaccharide provides a low-cost alternative to fractionated dextrans for use in aqueous two-phase, two-polymer systems with polyethylene glycol (PEG). The narrow molecular-weight distribution (Mw/Mn of 1-2) and low viscosity at high concentration of AG can be exploited for reproducible separations of proteins under a variety of conditions. The AG/PEG systems were used with success for batch extractive bioconversions of cornstarch to cyclodextrin and glucose. 

A sedimentation coefficient distribution—either c s) versus 5 or g (s) vs. s—for a polysaccharide can also be converted into an apparent molecular weight distribution if the conformation of the polysaccharide is known or can... 

Molecular weights of polysaccharides in solution can also be measured by osmotic pressure and light scattering. Osmotic pressure yields the number average molecular weight, which can be usefully used with Mw from sedimentation equilibrium as a measure of polydispersity Preston and Wik [28] have done this for example with hyaluronic acid. The ratio Mw/Mn the polydispersity index is often given as a measure of polydispersity, and can be related to the width of a molecular weight distribution via the well-known Herdan [96] relation ... 

Fujita [38] showed that for a log-normal distribution of molecular weights (the usual case for polysaccharides) Mz/Mw = Mw/M . 

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... 

---