Studies On Hydrophobic Adsorption Equilibria And Kinetics Of Proteins

Bovine serum albumin (BSA) and lysozyme (LYS) were chosen as model proteins. The effects of salt concentration, salt type, pH in mobile phase and hydrophobic ligand density of the stationary phase on the adsorption equilibria of proteins to hydrophobic adsorbent, Phenyl Sepharose CL-6B FF were studied.The adsorption equilibria of BSA are in good accordance with the Langmuir isotherm model. Adsorption is prompted by the increase of salt concentration and ligand density, the hydrophobic interaction between BSA and Phenyl Sepharose decreases with the increase of pH in buffer system. Na2SO4 is more effective to promote the hydrophobic adsorption of BSA than (NH4)2SO4. The influence of salt type and salt concentration on BSA adsorption could be well explained by the solvophobic theory. Electrostatic interaction may influence the adsorption equilibria of lysozyme to Phenyl Sepharose.The adsorption kinetics of BSA into Phenyl Sepharose were analyzed by using pore diffusion model, and the effective diffusion coefficient, De, was obtained. Salt concentration may have impact on De, while the hydrophobic ligand density and the initial concentration of BSA influence De slightly. The Exponentially modified Langmuir (EML) isotherm was used to characterize the adsorption of BSA onto Phenyl Sepharose, it was shown that the effects of salt concentration on the hydrophobic adsorption of BSA could be described by EML on the whole.