Electrochemical studies of the interaction of clarithromycin with bovine serum albumin.

The interaction of clarithromycin (CAM) with bovine serum albumin (BSA) was investigated in pH 4.5-8.0 phosphate buffer solutions in which three irreversible reduction waves P(1), P(2) and P(3) of CAM appeared on linear-sweep voltammetry on a static dropping mercury working electrode. In the acidic media, with the addition of BSA into the CAM solution, a new electrochemically active complex was formed and there was interaction between the carbonyl group C=O in the C-9 position of CAM and BSA. It was found that electrostatic and hydrophobic forces played an important role in the binding reaction. However, new electrochemically non-active complexes were formed at physiological pH condition. The study showed that the formation constant and formation ratio of the interaction between CAM and BSA were 1.51 x 10(12) and 3:1 for P(2) wave, and 4.53 x 10(5) and 1:1 for P(3) wave, respectively. The ion strength enhanced the hydrophobic interaction between CAM and BSA.