Adsorption isotherms and thermodynamics of alpha-lactalbumin on an anionic exchanger

作者：Fontan Rafael C I^*; Minim Luis A; Bonomo Renata C F; da Silva Luis Henrique M; Minim Valeria P R

来源：Fluid Phase Equilibria, 2013, 348: 39-44.

DOI：10.1016/j.fluid.2013.03.027

• Adsorption isotherms
• Ion exchange
• Enthalpy
• Entropy
• Gibbs free energy

The investigation of protein adsorption phenomena on solid surfaces is important for the development of purification processes. Knowledge of this equilibrium and the induced conformational changes of proteins is essential for its understanding. Thus, the adsorption behavior of alpha-lactalbumin (alpha-la) on an anionic exchange resin, Streamline (R) QXL, at pH 7.4 and four different temperatures was studied. It was observed that the adsorptive capacity decreases with higher temperatures. Five isotherm models were fitted to the experimental data, where the Langmuir and Jovanovic models were the best. The Toth model was also reduced to the Langmuir model. The results indicated that the adsorption process is homogeneous, indicating Langmuirian behavior. Thermodynamic analysis based on the van't Hoff equation shows a spontaneous, endotherrnal and entropy driven process. The process became more spontaneous at higher temperatures, possibly less endothermal and unfold of the protein structure caused a negative effect on entropy associated to or-la conformational changes and small ions binding to the adsorbent, reflected by the reduction of maximum adsorptive capacity of the adsorbent.

• 出版日期2013-6-25