Study on the interaction between clozapine and bovine serum albumin

The interaction between bovine serum albumin (BSA) and clozapine (CZP) was investigated using fluorescence spectroscopy (FS) and ultraviolet spectroscopy (UV). The experimental data showed that the CZP could insert into the BSA and quench its intrinsic fluorescence by forming CZP–BSA complex. It was found that both static quenching and non-radiation energy transfer were the main reasons leading to the fluorescence quenching. The apparent binding constants (K) between CZP and BSA were determined to be 1.26 × 105 (300 K) and 1.67 × 104 (310 K). The binding sites (n) were 1.1 ± 0.1. According to the Förster theory of non-radiation energy transfer, the binding distances (r) between CZP and the tryptophan residue of BSA were 2.99 nm (300 K) and 2.74 nm (310 K), respectively. The thermodynamic parameters showed that the interaction between CZP and BSA was driven mainly by hydrogen bonding interactions and Van der Waals force.