Molecular weight of polysaccharides

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 ... 

II. The Molecular Weights of Polysaccharides Containing One Type of Structural Unit. 386... 

The molecular weight of the debenzylated polysaccharide was estimated to be 2,800 by GPC measurements with water eluent. This value is in very good agreement with the calculated value (2,600) based on the molecular weight of polysaccharide 2 before the debenzylation. The debenzylated... 

The work discussed in this article serves to illustrate the applicability of gel chromatography to a wide variety of carbohydrates. The technique can be used not only as a means of fractionation but also, provided that the relationship between molecular weight and such other molecular parameters as size and shape remains constant, as a method of estimating the molecular weights of polysaccharides. Often, information derived from gel chromatography has proved useful in structural elucidation. 

Table VIII summarizes the results of measurements of molecular weights of polysaccharides containing one type of structural unit.

F. W. Parrish and W. J. Whelan, Determination of molecular weights of polysaccharides by overoxidation with periodate. Nature, 183 (1959) 991-992. 

Secondly, we investigated the effect of coating with these polysaccharides on the barrier function of liposomal membrane. The spontaneous release of carboxyfluorescein (CF) encapsulated in the interior of liposomes as a function of time was investigated at 50.0 °C (Fig. 3). Coating the outer surface of liposomes with these polysaccharides brought about several fold decrease in the permeability for CF. The substitution degree of acyl residues to behave as an anchor rather than the molecular weight of polysaccharide seems more important to coat conveniently the surface of liposomes. 

Molecular weights of polysaccharides may be determined by measuring the osmotic pressure of dilute solutions. The osmotic pressure at infinite dilution, obtained by extrapolating a number of measurements at various low concentrations, is a fimction of the molecular weight as shown by the modified van t Hoff formula. 

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