Interactions between isoprenaline hydrochloride and bovine serum albumin (BSA) in capillary zone electrophoresis and affinity capillary electrophoresis.

Capillary zone electrophoresis (CZE) and affinity capillary electrophoresis (ACE) were developed to investigate the interactions between isoprenaline hydrochloride (IH) and bovine serum albumin (BSA). In CZE, the binding constant (Kb) was 4.07 x 10(4) M(-1) (298 K) and 4.76 x 10(4) M(-1) (310K) using the Scatchard analysis. The number of binding sites (n) in this interaction was approximately one (n approximately equal 1). Furthermore, thermodynamic parameters, such as changes in Gibbs free energy (deltaG), enthalpy (deltaH), and entropy (deltaS) of the binding procedure were also obtained. At 298 K, deltaG, deltaH, and deltaS were -26.30 kJ x mol(-1), 10.02 kJ x mol(-1), and 0.12 kJ x mol(-) x K(-1), respectively. The deltaG at 310K was -27.76 kJ x mol(-1), whereas the deltaH and deltaS at 310 K were identical with that at 298 K. In ACE, a more reliable parameter, mobility ratio (M), was applied in the calculation of Kb. Kb (310K) obtained through this method was 9.80 x 10(4) and 9.24 x 10(4) M(-1) when IH and BSA were added to the buffer in varying concentrations, respectively. The obtained Kb may help in gaining some insights on the possible drug/protein interactions and in the early evaluation of the pharmacokinetic profile of the drug during cardiovascular drug screening.