A correlation of thermodynamic parameters with size of copper-chelated albumin aggregates

Protein conformations are strictly related to its biological function, and the variation in the structure has a major impact on human health. Metal ions are known to participate in the numerous severe pathological transformations that lead to protein aggregation. We explored the binding of Cu(II) ions to albumin with variation in extent of aggregation. The proportion of aggregates of albumin is varied by changing the time of thermally induced aggregation at the temperature of 65 °C. Utility of isothermal titration calorimeter (ITC) to study the interaction of aggregated protein with copper has not been explored yet. Establishing the association between the size of aggregates and thermodynamic parameters obtained on interaction between aggregated proteins with the metal ion will prove beneficial for future scientific applications of drug-protein interactions. We have determined the thermodynamic parameters of metal ion binding to aggregated bovine serum albumin. The size and aggregation of protein was investigated by using dynamic light scattering and size exclusion chromatography respectively. We have found that the electrostatic interaction between the aggregates and the Cu(II) is predominant.