Interaction of human serum albumin with N-(4-ethoxyphenyl)-N′-(4-antipyrinyl) thiourea using spectroscopies and molecular modeling method

The interaction between N-(4-ethoxyphenyl)-N′-(4-antipyrinyl) thiourea (EPAT) and human serum albumin (HSA) was studied by fluorescence spectroscopy in combination with UV absorption spectroscopy. The intrinsic fluorescence of human serum albumin was quenched by EPAT through a static quenching procedure. The binding constants of EPAT with HSA were estimated according to the fluorescence quenching results at different temperatures. The binding distance was obtained and the binding force was suggested to be mainly hydrophobic force, which was in accordance with the study of molecular model. The effect of common ions on the binding constants was also investigated. A new fluorescence spectroscopy assay of the proteins is presented, and results were very satisfactory.