Abstract: The binding reaction between topotecan hydrochloride (THC) and human serum albumin (HSA) was studied by fluorescence and UV-Vis absorption spectra. The binding equilibrium constant, number of binding site and thermodynamic parameters were calculated. The distance between the binding site and tryptophan residue is 3.63 nm. The study of molecular simulation indicated that topotecan hydrochloride bound within the subdomain IIA of human serum albumins and the interaction between topotecan hydrochloride and HSA was dominated by hydrophobic force. In addition, both the residues Ala-291 and Asp-256 of HSA formed hydrogen bonds with topotecan hydrochloride, respectively.

Key words: THC, HAS, Fluorescence quenching, Binding reaction, Molecular simulation