Volume 7, Number 3, p.p. 97–102
Calorimetric study of bovine and human serum albumins and their complexes with bilirubin
M. Khvedelidze,* T. Mdzinrashvili, A. Trapaidze, E. Kortkhondjia and G. Mrevlishvili
I. Javakhishvili State University, 3 Chavchavdze Ave, 0128 Tbilisi, Georgia
Thermodynamic properties of bovine and human serum albumin solutions were studied using a differential scanning microcalorimeter, i.e. the dependence of partial heat capacity on temperature was determined. The predenaturation and main changes of the protein’s partial heat capacity during thermal denaturation were obtained. Deconvolution of the partial heat capacity function indicates that the process of denaturation consists of three transitions; each of them corresponds to the melting of three different structural domains. Analysis of the microcalorimetric melting curves of the albumin-bilirubin complex together with the thermodynamic parameters of the domains show that the bilirubin binding is localized in domain II of the albumin molecule.
Keywords: bilirubin, calorimetry, human and bovine serum albumin, ligand connexion, protein denaturation, thermodynamics