Viscometry and sedimentation equilibrium of partially hydrolyzed hyaluronate: Comparison with theoretical models of wormlike chains

Autor: Robert L. Cleland
Rok vydání: 1984
Předmět:
Zdroj: Biopolymers. 23:647-666
ISSN: 1097-0282
0006-3525
DOI: 10.1002/bip.360230406
Popis: Fractionated samples of sodium hyaluronate of low molecular weight were used to calibrate the carbazole method for glucuronyl analsis and to determine the density increment (based on dry weight) of 0.444 (±0.003) mL/g in water and 0.386 (±0.003) mL/g for samples dialyzed against 0.2M NaCl. Weight-average molecular weights obtained by high-speed sedimentation equilibrium were used to calibrate the limiting viscosity number [η] in 0.2M NaCl, which gave [η]/Mw = 0.0028 (±0.0002) mL/g, valid to Mw = 0.0028 (±0.0002) mL/g, valid to Mw = 105. Experimental data from this work and the literature, including viscosity and light- and small-angle x-ray scattering measurements, were compared to theoretical chain models of the Kratky-Porod (KP) wormlike and the helical wormlike (HW) chain, as treated by Yamakawa and collaborators. Although either model could be fitted to experimental data about equally well with consistent parameters, provided those for the HW chain were of weakly helical nature, calculation of the unperturbed meansquare end-to-end distance as a function of chain length from a conformational model favored the KP chain alternative. The parameters that provide the best fit to experimental data for the KP wormlike model are a persistence length of 4.5–5 nm and a diameter of 1.1 nm. The latter is resonable for a hydrated hydrodynamic cylinder in view of the approximate unhydrated value of 0.7 nm estimated from the density increment.
Databáze: OpenAIRE
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