Studies on the interaction between 1-hexylcarbamoyl-5-fluorouracil and bovine serum albumin

The interaction between anti-tumor drug, 1-hexylcarbamoyl-5-fluorouracil (Carmofur), and bovine serum albumin (BSA) were studied by spectroscopic methods including fluorescence spectroscopy, circular dichroism (CD) and UV–Visible absorption spectrum. The quenching mechanism of fluorescence of BSA by Carmofur was discussed. The number of binding sites n and apparent binding constant Kb was measured by fluorescence quenching method. The thermodynamic parameters DH, DG, DS at different temperatures were calculated and the results indicate the binding reaction is mainly entropy-driven and hydrophobic forces played major role in the reaction. The distance r between donor (BSA) and acceptor (Carmofur) was obtained according to Fo¨rster theory of non-radiation energy transfer. CD spectrum were used to investigate the structural change of BSA molecules with addition of Carmofur, the result indicates that the secondary structure of BSA molecules is changed in the presence of Carmofur. q 2004 Elsevier B.V. All rights reserved