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  • 1
    Electronic Resource
    Electronic Resource
    The effects of pH on hyaluronate as observed by light scattering (1989)
    New York : Wiley-Blackwell
    Biopolymers 28 (1989), S. 1981-2000 
    Details
    ISSN: 0006-3525
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Hyaluronate was investigated over a wide pH range, and at near zero and intermediate ionic strength, using dynamic and total intensity light scattering. Commercially obtained rooster comb hyaluronate was purified, and solutions were prepared in pure water by low-power bath ultrasonication and subsequent filtering. These solutions were of low polydispersity and appeared to contain single molecules of hyaluronate. Despite the absence of added electrolyte, these solutions yielded well-behaved Zimm plots. Increasing ionic strength and changing pH decreased radii of gyration and increased diffusion constants. Except for what appeared to be slow hydrolysis at either extreme of pH, molecular weights remained constant under all pH and ionic strength conditions. Under all solvent conditions investigated, diffusion coefficients increased with decreasing hyaluronate concentration. Unsonicated, lightly centrifuged solutions without added electrolyte were polydisperse, and their light scattering intensity was dominated by what appeared to be stable hyaluronate aggregates. The results are interpreted in terms of the polyelectrolyte properties of hyaluronate and its tendency to form stable entanglements, especially at low ionic strength. Previous light scattering studies in the literature on hyaluronate have shown widely varying results. The present article briefly reviews this literature and attempts to explain the variation among the previous results, emphasizing the Kuhn statistical segment length as an indicator of whether results are influenced by polydispersity or contaminants causing hyaluronate aggregation.
    Additional Material: 6 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/bip.360281114
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  • 2
    Electronic Resource
    Electronic Resource
    Aggregates and other particles as the origin of the “extraordinary” diffusional phase in polyelectrolyte solutions (1992)
    New York : Wiley-Blackwell
    Biopolymers 32 (1992), S. 1105-1122 
    Details
    ISSN: 0006-3525
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The “extraordinary” diffusional phase (EP) at low ionic strength, and the conditions for 1 its removability by filtration were investigated for dilute solutions of the following linear polyelectrolytes: poly(L-lysine), heparin, chondroitin-6-sulfate, hyaluronate, polystyrene sulfonate, and variably ionized polyacrylamide. The EP was not present for all the different types studied, and for heparin, for example, the phase was present only for samples from certain sources. In all cases the phase was removable by filtration through sufficiently small pore-size membranes. Once filtered, the EP remained absent for over one week. It is concluded that the extraordinary diffusional phase consists of fairly stable polyelectrolyte aggregates, and sometimes also includes other very small particulate impurities. These aggregates and other small particles are thought to be present, or at least nascent, in the dry polyelectrolyte material, so that their properties may depend critically on the manner in which such dry material is produced. Tests for “reversibility” of the EP by cycling between high and low Cs by dialysis further confirm these conclusions. The evidence is thus against the EP representing any type of temporal aggregates or local ordering, at least for the linear polyelectrolytes studied in this work Rather, due to the extremely feeble scattering of ordinary polyelectrolytes at low ionic strength, the weak scattering from residual aggregates and other particles, not removed by ordinary filtration and centrifugation procedures, give autocorrelable scattering signals with long decay times. The “loss” of the extraordinary phase as ionic strength increases appears to be due simply to the weak EP scattering signal getting buried in the sharply increasing scattering from the ordinary polyelectrolyte phase. Model calculations based on experimental data support this latter conclusion. © 1992 John Wiley & Sons, Inc.
    Additional Material: 6 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/bip.360320818
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  • 3
    Electronic Resource
    Electronic Resource
    Apparent persistence lengths and diffusion behavior of high molecular weight hyaluronate (1990)
    New York : Wiley-Blackwell
    Biopolymers 30 (1990), S. 1101-1112 
    Details
    ISSN: 0006-3525
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: High purity, high molecular weight hyaluronate from bacteria and rooster comb exhibited clear polyelectrolyte properties, as observed by static and dynamic light scattering. The scattered intensity of hyaluronate solutions increased markedly with ionic strength, while the radii of gyration decreased. Apparent persistence lengths within the wormlike chain model in the coil limit were estimated as a function of ionic strength. The total apparent persistence length varied from about 87 Å in the high ionic strength limit to nearly 400 Å at 1 mM added NaCl. The apparent electrostatic persistence length varied approximately as the inverse square root of the ionic strength. Deviations from the theoretically predicted inverse ionic strength dependence were investigated in terms of excluded volume effects. Dynamic light scattering yielded “ordinary phase” diffusion coefficients whose dependence on polymer and salt concentration agreed reasonably well with hydrodynamic coupled mode theory in the linear limit. Extrapolations to infinite polymer dilution at fixed salts yielded, surprisingly, a constant diffusion coefficient. Thus, there was no evidence of either polyion expansion or electrolyte friction effects in the infinite dilution diffusion coefficients. Since clear evidence for polyion expansion was seen in the static scattering, it is thought that the relative stiffness and consequent openness of the hyaluronate coils lead to partial free draining behavior. There was no evidence for an “extraordinary phase” under no added salt and low added salt conditions. The overall results are contrasted with the very different behavior previously reported for medium purity hyaluronate from animal sources.
    Additional Material: 6 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/bip.360301110
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  • 4
    Electronic Resource
    Electronic Resource
    New characteristic signatures from time-dependent static light scattering during polymer depolymerization, with application to proteoglycan subunit degradation (1995)
    New York : Wiley-Blackwell
    Biopolymers 35 (1995), S. 435-450 
    Details
    ISSN: 0006-3525
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Models were developed for the time-dependent light scattering intensity for simply branched (“comb”) polymers undergoing one or more of three distinguishable degradation mechanisms: (a) stripping off the side chains, (b) randomly degrading off the side chains, and (c) randomly degrading the backbone. The model equations were applied to the analysis of different types of degradation of simply branched biopolymers - bovine nasal cartilage proteoglycan subunits (or “monomers”); NaOH stripped off the glycosaminoglycan (GAG) chains from the protein backbone [mechanism (a)], whereas hyaluronidase seemed to randomly cleave the GAG side chains [mechanism (b)], and HCl both stripped the GAG side chains and randomly cleaved the protein backbone [combined mechanisms (a) and (c)]. The reactions were followed with time-dependent multiangle, static light scattering. The time-resolved total scattering technique allowed degradation rate constants and percentage of material in the branched polymer backbone and side chains to be determined, in addition to the mechanisms involved. These new time-dependent light scattering profiles are added to the growing library of functions from which deductions can be made concerning polymer structure and associated degradation mechanisms and kinetics. These conclusions, drawn from time-dependent “batch” light scattering, are substantiated by preliminary size exclusion chromatography results and chemical binding assays for sulfated GAGs. © 1995 John Wiley & Sons, Inc.
    Additional Material: 11 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/bip.360350503
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  • 5
    Electronic Resource
    Electronic Resource
    Phase behavior of aqueous gelatin/oligosaccharide mixtures (1997)
    New York : Wiley-Blackwell
    Biopolymers 41 (1997), S. 607-622 
    Details
    ISSN: 0006-3525
    Keywords: polymer solution phase behavior ; gelatin ; oligosaccharides ; gelatin and oligosaccharides ; compatibility of/dilute solution properties of/light scattering of/size exclusion chromatography of ; size exclusion chromatography and light scattering detection ; Flory Huggins ; Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The phase behavior of aqueous mixtures of gelatin and oligosaccharides above their gelation temperature is investigated experimentally, and rationalized according to a simple multicomponent Flory-Huggins model. When the gelatin is only weakly charged, entropic considerations dominate and it is found that the cloud point curve of the mixtures is extremely sensitive to the molecular weight distribution of the oligosaccharide. Even very small quantities of long-chain oligosaccharides present in an otherwise short-chain oligosaccharide population can radically reduce the compatibility. Added salt does not significantly affect the phase diagram, although a strong effect on the kinetics of phase separation is seen. Lowering the pH increases the electrostatic charge on the gelatin and strongly enhances the compatibility. Because the kinetics of gelation and phase separation are different, gelation can freeze in nonequilibrium states. Therefore, all phase diagrams were determined well above the gelation temperature (about 37°C). © 1997 John Wiley & Sons, Inc. Biopoly 41: 607-622, 1997
    Additional Material: 15 Ill.
    Type of Medium: Electronic Resource
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  • 6
    Electronic Resource
    Electronic Resource
    Random coil scission rates determined by time-dependent total intensity light scattering: Hyaluronate depolymerization by hyaluronidase (1990)
    New York : Wiley-Blackwell
    Biopolymers 30 (1990), S. 1073-1082 
    Details
    ISSN: 0006-3525
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: A recently developed theory of the light scattering by random coils undergoing random scission is applied to the digestion of hyaluronate by hyaluronidase. The time dependence of the scattered light from solutions undergoing digestion was monitored. Working at a high angle with high molecular weight hyaluronate allowed the use of a powerful approximation for determining initial velocities and the Henri-Michaelis-Menten coefficients, without explicit knowledge of the hyaluronate molecular weight, radius of gyration, second virial coefficient, or polydispersity. Effects due to a molecular weight dependent second virial coefficient and to non-Gaussian behavior are briefly considered. Assays were performed over nearly two orders of magnitude in substrate concentration. The initial velocities are compared with those obtained by a standard reducing sugar assay, which was performed on identical samples. The main advantages of the light scattering assay procedure over the more traditional assays are that many relatively high-precision data points can be quickly and automatically collected with simple apparatus, and that the technique is most sensitive for the initial period of digestion, where the other assays are least sensitive. The shapes of the scattering curves also provide evidence that hyaluronate in these solutions is not a stable double strand and that the hyaluronidase cleaves bonds randomly. The curves also indicate that enzyme deactivation occurs, which accounts for the lower velocities yielded by the slower reductimetric assay, which is measured over longer initial periods.
    Additional Material: 4 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/bip.360301108
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  • 7
    Electronic Resource
    Electronic Resource
    High osmotic stress behavior of hyaluronate and heparin (1992)
    New York : Wiley-Blackwell
    Biopolymers 32 (1992), S. 219-238 
    Details
    ISSN: 0006-3525
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Using polyethylene glycol and dextran as osmotic stressing agents, the concentrations of hyaluronate and heparin were measured as a function of osmotic pressure II over the range of 0.03 to nearly 50 atmospheres. The experimental results were analyzed in terms of the Donnan osmotic pressure, the virial expansion, and Flory's first neighbor interaction parameter. In addition, II was looked at as a function of the reciprocal cube root of the concentration, which represents an average intermonomer spacing at high concentrations. The decay lengths in the so-called hydration region were found to be around 2.6 Å and negligibly salt dependent. In the electrostatically dominated region the decay lengths were found to be dependent on the ionic strength, but not simply so. The osmotic compressibilities were also calculated, and were compared to compressibility data of corneal stroma and articular cartilage. These latter compressibilities were close to those for the pure hyaluronate and heparin, strengthening the evidence that glycosaminoglycans (GAGs) are largely responsible for connective tissue compressibility. Higher compressibilities for previously reported GAG data is thought to be related to the protein content of those samples.
    Additional Material: 10 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/bip.360320304
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  • 8
    Electronic Resource
    Electronic Resource
    Data evaluation for unified multi-detector size exclusion chromatography  -  molar mass, viscosity and radius of gyration distributions (1995)
    Weinheim : Wiley-Blackwell
    Macromolecular Chemistry and Physics 196 (1995), S. 1539-1575 
    Details
    ISSN: 1022-1352
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: The output of a size exclusion chromatography (SEC) system was connected to a single capillary viscometer, a multi-angle laser light scattering detector (MALLS) and a refractive index detector (RI). This provides absolute distributions of molar mass, radius of gyration and reduced viscosity, which are valuable both for practical polymer characterization and as tests of physical polymer theories. The instrument interfacing is described, along with the method of data analysis. A quantitative investigation of systematic and random sources of error and their influence on polymer characterization is made. An experimental example using a biopolyelectrolyte (hyaluronate), including complete error analysis, is presented, along with other data. Although the emphasis here is on aqueous SEC, most of the principles should carry over to organic phase SEC. A simultaneous, in-line comparison of a low-angle laser light scattering (LALLS) detector and MALLS detectors was also made. The dangers of ‘universal calibration’ for hydrosoluble polymers are also illustrated.
    Additional Material: 9 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/macp.1995.021960515
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  • 9
    Electronic Resource
    Electronic Resource
    Data evaluation for unified multi-detector size exclusion chromatography - molar mass, viscosity and radius of gyration distributions (1996)
    Weinheim : Wiley-Blackwell
    Macromolecular Chemistry and Physics 197 (1996), S. 2075-2075 
    Details
    ISSN: 1022-1352
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/macp.1996.021970623
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