Abstract:

The interaction between bovine serum albumin (BSA) and gatifloxacin (GT) was investigated using affinity capillary electrophoresis (ACE) method, mobility-shift method. The mobility ratio of the internal standard and the sample was used to calculate the binding constant Kb of bovine serum albumin and gatifloxacin. At first, 20 mmol/L, pH 7.4 sodium phosphate buffer solution （PBS） added with 0-1000 μmol/L GT as running buffer was used, BSA as the sample was used. Kb calculated from this experiment was 4.4×104 L/mol. Then 0-12.5 μmol/L BSA was used as an additive to do the ACE experiment, the Kb obtained was 4.2×104 L/mol. The two values matched well with each other. In order to improve the shape of the peak and restrain the adsorption of BSA to the internal wall of the quartz column, in the second method, 0.25 mol/L Gly and 0.5 mmol/L ethylenediamine tetracetate （EDTA） were added to the running buffer, and 0.5%sodium dodecyl sulfate （SDS） solution was used to rinse the column. Satisfactory effect was obtained. The Kb from fluorescence method was also calculated with a value of 2.7×104 L/mol. This work demonstrated that the determination of the binding constant by ACE is simple with high performance.

Key words: binding constant , bovine serum albumin （BSA）, gatifloxacin, affinity capillary electrophoresis (ACE)