The interaction of tributyltin (TBT), the main components of antifouling paint of ships, and its degradation products of monobutyltin (MBT) and dibutyltin (DBT) with human serum albumin (HSA) was investigated by ultraviolet, fluorescence and circle dichromism spectra. The influences of the concentration, acidity, organic solvent such as ethanol and ionic strength on the interaction of butyltin compounds and HSA molecule were examined to find that the interaction of butyltin compounds and HSA was dual. The butyltin compounds had not only coordinate but also hydrophobic actions with HSA molecule, which led to the destruction of the secondary structure of HSA molecule, decrease of content of α-spiral structure and transformation of conformation. Generally, MBT is inclined to act with HSA molecule through coordination action, while TBT is inclined to do with HSA molecule through hydrophobic action, and DBT can act with HSA molecule adopting both actions synchronously.

Key words: butyltin compound, human serum albumin, interaction