Binding of daunorubicin to human serum albumin using molecular modeling and its analytical application

This study was designed to examine the interaction of daunorubicin with human serum albumin (HSA) for the first time by fluorescence spectroscopy in combination with UV absorption and molecular modeling under simulative physiological conditions. The quenching mechanism was suggested to be static quenching according to the fluorescence measurement and the linearity of Scatchard plot indicated that daunorubicin bound to a single class of binding sites on HSA. The thermodynamic parameters, enthalpy change (Delta H) and entropy change (Delta S) were calculated to be - 16.13 kJ/mol and 27.86 J/(mol K), according to the Vant'Hoff equation. These data suggested that hydrophobic interaction was the predominant intermolecular forces stabilizing the complex, which was in good agreement with the results of molecular modeling study. In addition, the effects of common ions on the binding constant of daunorubicin-HSA complex were also discussed at room temperature. Moreover, the synchronous fluorescence technique was successfully employed to determine the total proteins in serum, urine and saliva samples at room temperature under the optimum conditions with a wide linear range and satisfactory results. (C) 2007 Elsevier B.V. All rights reserved.