Preparation and characterization of polysaccharide phosphates

Whistler, Roy L.; Towle, Gordon A.

doi:10.1016/0003-9861(69)90555-4

Cited by 29 publications

(8 citation statements)

References 12 publications

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“…Dextran phosphate was prepared from the purified parent dextran (Sigma, M w = 2.4 · 10 5 g mol -1 ) according to the method of Whistler and Towle. 13 The degree of substitution by phosphate groups, determined by elementary analysis and potentiometric titration, was 0.5 per glucose ring. Thus, the average value of DP is 1.6.…”

Section: Methodsmentioning

confidence: 99%

“…The corresponding degrees of counterion binding, 0 1 and 0 2 , can be calculated from the two variable theory of Manning. 12 It holds, 1 +ln(--01 -)= -2~(1-0 1 -20 2 )ln(l-e-Kh) (13) Vecs,1 ln(02/c., 2) =In(~)+ 2 ln( 2 · 7201 ) It should be noted that eq 13 and 14 are valid only when the total ionic strength sufficiently exceeds the polyion concentration cp, so that the influence of the polyion on the small ion activities through long range interactions can be neglected. That is, the condition cp/ Ceo« 1, where ceo is the total coion concentration (ce0 =Cs,l +2cs,2-cp), must be fulfilled.…”

Section: Degrees Of Counterion Bindingmentioning

confidence: 98%

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Studies of Polyelectrolyte Solutions VI. Effects of Counterion Binding by Dextran Sulfate and Dextran Phosphate in Aqueous/Organic Solvents

Baré

Nordmeier

1996

Polym J

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ABSTRACT:The influence of the solvent on the degree of counterion binding of dextran sulfate and dextran phosphate is studied by activity measurements, dye-spectroscopy, and static light scattering. The solvents used are binary mixtures of water and organic solvents such as acetone, alcohol, and formamide. The mixing ratio is varied over a wide range in order to obtain different solvent dielectric constants. The results of investigations are as follows. First of all, in pure water the alkali ions are bound by dextran sulfate in the order Cs+ > K + >Na+> Li+, i.e., the degree of counterion binding for Li+ is lowest while that for Cs+ is largest. The inverse ion sequence is observed for dextran phosphate. In mixed solvents the ion sequence depends on the mixture used. Secondly, there exists no universal correlation between the dielectric constant of the solvent and the degree of counterion binding. However, it is common to all aqueous/organic solvent mixtures that the degree of counterion binding decreases as the fraction of the organic compound in the solvent increases. Thirdly, condensation theory is not valid in mixed solvents, while the Poisson-Boltzmann approach may be applied. Taking into account the size of the solvated small ions we find that the type of counterion binding of a divalent counterion, such as Mg 2 +, depends on the kind of the univalent counterions added in excess. For water/n-propanol it seems that in the presence of Li+, Mg2+ is bound delocalized, while in the presence of K +, Mg 2 + is bound by site binding. Fourthly, in water/formamide and water/dimethyl sulfoxide (DMSO) the organic solvents are adsorbed preferably by dextran sulfate. As a consequence, the dielectric constant at the polyion surface differs from that of the bulk solvent. Nevertheless, if these changes are taken into account, the predictions of condensation theory remain contradictory to the results of measurements.KEY WORDS Dextran Sulfate / Dextran Phosphate / Counterion Binding / Mixed Solvents / Activity Coefficients / Dielectric Constants / Dye Spectroscopy / Static Light Scattering / There has been great interest in studying the interactions between polyion and simple electrolytes, as this information provides a key to the understanding of biological processes since many biopolymers are polyelectrolytes. A well established result has been that an extra amount of counterions will bind on the polyion of almost all bulk counterions. For instance, in previous reports, 1 -3 we have shown that the polyion charge density and the kind of charged groups play an important role for the degree of counterion binding, but it is also expected that the solvent, in which the polyelectrolyte chains are dissolved, have some influence. Studies in water and aqueous/organic solvent mixtures are therefore very important. The reasons are:I. A certain property of the solvent such as a define value of the dielectric constant, s,, or a particular value of the refractive index, n, can be more precisely adjusted in mixed than in single solvents. ...

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Section: Methodsmentioning

confidence: 99%

Section: Degrees Of Counterion Bindingmentioning

confidence: 98%

Studies of Polyelectrolyte Solutions VI. Effects of Counterion Binding by Dextran Sulfate and Dextran Phosphate in Aqueous/Organic Solvents

Baré

Nordmeier

1996

Polym J

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“…It was shown that the polysaccharide phosphates synthesized chemically by the phosphorylation of several common polysaccharides with polyphosphoric acid by the method of Whistler and Towle [10] were capable of evoking serum interferon at a significant level. The rabbit serum interferon induced by these phosphates was found to be similar in properties to those induced by bacterial endotoxins described by Ho [6], e.g., the viral inhibiting activity was susceptible to treatments by heat, low pH and tryptic digestion.…”

Section: Discussionmentioning

confidence: 99%

“…The above finding seemed to suggest the postulation that most of the acidic polysaccharides possessing phosphate moieties might also be able to behave as strong interferon-inducing substances. Phosphorylated polysaccharides, synthesized chemically by the reaction of several ordinary polysaccharides and polyphosphoric acid according to the recent description of Whistler and Dubin [10] were utilized in the present study. …”

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confidence: 99%

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1972

Japanese Journal of Microbiology

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Readily available polysaccharides, amylopectin, amylose, dextrin, and yeast mannan, were chemically pliosphorylated using polyphosphoric acid in the presence of a tertiary amine, and the resultant phosphates were examined for their interferon-inducing activity in rabbits employing an assay system consisting of a primary culture of rabbit kidney cells and vesicular stomatitis virus. All the phosphates were shown to be active as interferon inducer, and, especially , the activity of those containing more than 2% phosphorus were quite strong. Interferons evoked by the above phosphates resembled those induced by bacterial endotoxin, e.g., the viral inhibiting activity was susceptible to heat treatment, low pH and tryptic digestion. Since all the parent polysaccharides showed no interferon-inducing activity, it is reasonable to assume that the active center of these inducers might reside or be due to the anionic phosphate groups.We have previously reported that the phosphomannans of the genus Hansenula are able to evoke rabbit serum interferon in considerable amounts. The above finding seemed to suggest the postulation that most of the acidic polysaccharides possessing phosphate moieties might also be able to behave as strong interferon-inducing substances. Phosphorylated polysaccharides, synthesized chemically by the reaction of several ordinary polysaccharides and polyphosphoric acid according to the recent description of Whistler and Dubin [10] were utilized in the present study. MATERIALS AND METHODSPolysaccharide preparations employed.

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“…The resultant was concentrated and lyophilized to give phosphorylated fucoidan (PF1). [11] Fucoidan (2.0) was dissolved in 100 mL of formamide, then tributylamine (10 mL) and polyphosphoric acid (5.0 g) were added to the clear solution. The mixture was stirred for 24 h at room temperature, and then poured into ethanol (600 mL).…”

Section: Pocl 3 Methods [5]mentioning

confidence: 99%