[Study on the interaction between cinnamic acid and human serum albumin by fluorescence quenching method]

The albumin is the richest protein in blood circulatory system, which can combine with many drugs and play an important role in transporing protein. In the present work, the non-covalent interaction between human serum albumin and cinnamic acid was studied by using fluorescence quenching method. The results showed that cinnamic acid had a powerful ability to quench the fluorescence of human serum albumin at excitation and emission wavelengths of lambda(ex) = 286 nm and lambda(ex) = 340 nm, respectively, in the reaction solution of pH 7.4. The binding constants(K) at 37 and 47 degrees C were found to be 1.276 7 x 10(3) and 3.404 1 x 10(3) L x mol(-1), with the number of binding site(n) of 0.758 6 and 0.835 6, respectively, suggesting that the reaction temperature is advantageous for the binding reaction in a way. The changes in the thermodynamic parameters of binding interaction at 37 and 47 degrees C indicated that the main binding force between cinnamic acid and human serum albumin was hydrophobic force. These provide important information for studying the pharmacological effects of cinnamic acid and the influence of cinnamic acid on the configuration change of HSA.