Study of the complex coacervation mechanism between ovalbumin and the strong polyanion PSSNa: influence of temperature and pH
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We studied the complex between ovalbumin and long flexible poly-(sodium 4-styrene sulfonate) as a function of pH and temperature. We used various techniques [turbidimetry, conductometry, dynamic light scattering, viscosimetry, and ultra-small-angle light scattering (USALS)] to fully characterize the coacervate complex. Different phases of complexation versus temperature were determined by turbidimetric analysis (pHc, pHϕ1, and pHϕ2). The optimal protein/polyelectrolyte interaction occurred at pHopt 4. An increase in temperature made the hydrophobic interactions more favorable in the case of the soluble complex and complex coacervation phases (pH > pHϕ2). We systematically determined the activation energy to follow the conformational changes of the complex at different temperatures. At pHopt, the size of the formed complex showed a remarkable decrease with temperature increase. USALS was used to determine simultaneously the radius of gyration (Rg) and fractal dimension Df of the coacervate.
KeywordsElectrical conductivity Dynamic light scattering Ultra-small-angle static light scattering Complex coacervation Fractal dimension
This research was supported by the Ministry of Higher Education and Scientifi Research in Tunisia (MHESRT). We thank Pr. Luca cipelletti from Laboratory of Charles Coulomb University of Montpellier, France, for the help with the USALS software.
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