RESUMO
The objective of this study was to determine the thermodynamic parameters (Delta(tr)G, Delta(tr)H and Delta(tr)S) associated with lysozyme and conalbumin partitioning in aqueous two-phases systems (ATPS). Influence of salt type and polyethylene glycol (PEG) concentrations on the partition coefficient of lysozyme and conalbumin from egg white was studied. The evaluated ATPS were composed of PEG 1500 and inorganic salts (sodium citrate and sodium sulfate) at a temperature of 25 degrees C and pH 7.0, with PEG 1500 g mol(-1) concentrations of 14%, 16% and 18% (mass basis). Partitioning of lysozyme in PEG-citrate ATPS was enthalpically driven, however the PEG-sulfate ATPS was entropically driven. The tested systems can be employed for the separation of these two proteins in egg white, due to the fact that lysozyme migrates toward the polymeric phase and conalbumin to the saline phase in both ATPS. A high recovery of conalbumin in the saline phase of the PEG-sulfate ATPS was determined to be enthalpically driven.
Assuntos
Conalbumina/química , Muramidase/química , Termodinâmica , Conalbumina/isolamento & purificação , Muramidase/isolamento & purificação , Polietilenoglicóis/química , SolubilidadeRESUMO
Hydrophobic adsorption equilibrium data of the hen egg white proteins albumin, conalbumin, and lysozyme were obtained in batch systems, at 25 degrees C, using the Streamline Phenyl resin as adsorbent. The influence of three types of salt, NaCl, Na(2)SO(4), or (NH(4))(2)SO(4), and their concentration on the equilibrium data were evaluated. The salt Na(2)SO(4) showed the higher interaction with the studied proteins, thus favoring the adsorption of proteins by the adsorbent, even though each type of salt interacted in a distinct manner with each protein. The isotherm models of Langmuir, Langmuir exponential, and Chen and Sun were well fitted to the equilibrium data, with no significant difference being observed at the 5% level of significance. The mass transfer model applied simulated correctly adsorption kinetics of the proteins under the studied conditions.