Ionic binding of human serum albumin - Dependence on pH and ionic strength: A chromatographic approach

A chemometric method was applied to investigate the binding mechanism of Ca2+ and Mg2+ to human serum albumin (HSA) using a bio-chromatographic approach. The effects of the bulk solvent pH, its ionic strength and column temperature on the transfer of Ca2+ and Mg2+ from the bulk solvent to immobilized human serum albumin as a stationary phase were studied, Thermodynamic parameters corresponding to this transfer were determined from linear van't Hoff plots. Enthalpy-entropy compensation revealed that the ion binding mechanism to HSA was independent of ionic strength and pH, and the same for the two cations. The results corroborated the fact that HSA can be assimilated by a weak cation-exchanger and the Ca-HSA (or Mg-HSA) binding is controlled by electrostatic attraction for different "non specific" areas of serum albumin.