A high performance theory for thermodynamic study on the binding of human serum albumin with erbium chloride

Abstract

A thermodynamic study of the interaction between erbium(III) chloride (Er3+) and human serum albumin (HSA) was studied at pH=7.0, 27 and 37 oC in phosphate buffer by isothermal titration calorimetry (ITC). The present study reports the thermodynamic parameters that govern HSA-Er3+ interactions. The extended solvation theory was used to reproduce the enthalpies of HSA-Er3+ interactions over the whole range of Er3+ concentrations. The binding parameters recovered from the new model were attributed to the structural change of HSA and its biological activity. The results obtained indicate that there is a set of two identical binding sites for Er3+ ions with negative cooperativity. The enhancement of complex formation by Er3+ and concomitant increase in ΔS suggest that the metal ion plays a role in increasing the number of hydrophobic contacts. The binding parameters discovered from the extended solvation model indicate that the stability of HSA molecule is increased as a result of its interaction with Er3+ ions. © 2009 SIOC, CAS, Shanghai, & WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.