Characterization of enthalpic events in overloaded ion-exchange chromatography

Adsorptive behavior of α-lactalbumin on cation-exchange supermacroporous monolithic column

“…IEC is advantageous because separation typically occurs in the presence of aqueous buffers and hydrophilic surfaces as opposed to the harsher solvents and hydrophobic stationary phases used in reversed-phase chromatography. So, the desired protein does not readily denature, minimizing the loss of protein activity [20]. Moreover, IEC presents high capacity, relatively low cost and ability to maintain its characteristic under severe cleaning regimes [18].…”

An Analysis of the Interactions of BSA with an Anion-Exchange Surface Under Linear and Non-Linear Conditions

“…Endothermic heats of adsorption for protein ionexchange systems have been reported the literature (Bowen and Hughes, 1993;Raje and Pinto, 1998;Thrash Jr. and Pinto, 2002;Lin et al, 2000). The net driving force in such systems is an increase in the entropy.…”

“…Type I (Langmuir) isotherms were observed, and, as expected, a significantly greater capacity was measured in the absence of salt. For ion- exchange systems, this behavior is generally explained as the result of competition between protein and salt for the ion-exchange sites, or due to a reduction in the electrostatic potential of the adsorbent and/or the protein (Thrash Jr. and Pinto, 2002). It is also significant, for this anion-exchange system with very similar cations, that at high protein concentrations the capacity is a strong function of the cation type; KCl gives the highest capacity and LiCl the lowest Heats of adsorption were measured by calorimetry under overloaded (non-linear) conditions and the results obtained at 25 • C are shown in Fig.…”

“…It has been previously suggested (Thrash Jr. and Pinto, 2002) that the endothermic adsorptive heats arise primarily from repulsive interactions between adsorbed proteins possessing the same charge. If the potential around the protein significantly increases with temperature, then an increase in repulsion would explain the higher endothermic heats at 37 • C. To investigate this, the zeta potential for BSA in the presence of each salt was measured at 25 • C and 40 • C. As seen in Table 4, the change in zeta potential with temperature is negligible.…”

The effects of ligand chain length, salt concentration and temperature on the adsorption of bovine serum albumin onto polypropyleneglycol–Sepharose

“…It has been demonstrated previously that calorimetry provides valuable insight for overloaded protein chromatography. The equilibrium adsorption is dictated by the Gibbs free energy change for adsorption (∆G ads ), which is dependent upon the overall enthalpy change (∆ H ads ), which can be calculated from the heat of adsorption (Esquibel-King et al, 1999;Thrash and Pinto, 2001;Dias-Cabral et al, 2002, 2003Thrash and Pinto, 2002).…”