[Thermodynamics studies on the binding of rutin and serum albumin]

To study the binding of rutin and serum albumin (SA) in physiological condition and the quenching mechanism of the fluorescence of SA by rutin, the fluorescence method was used. The results shows that the emission spectra of BSA (HSA) in the presence and absence of rutin are different. The emission spectra of BSA (HSA) in the presence of rutin can be quenched. The quenching mechanism of rutin to SA was static quenching with non-radiation energy transfer with single molecule. The binding constants K(A), the number of binding sites n and the thermodynamic parameters of the reaction of rutin with SA were determined at different temperatures. At 295 and 310 K, for BSA, K(A)(L * moL(-1)) = 4.215 x 10(4) and 6.996 x 10(3) and n = 0.75 and 0.64, respectively; for HSA, K(A)(L * moL (-1)) = 2.660 x 10(4) and 4.110 x 10(3) and n = 0.70 and 0.60, respectively. The binding constants K(A) decreased with the increase in temperature, which means that rutin and SA have a quite strong ability to form a new complex-system. The main binding force was discussed by thermodynamic equation, and the result is that deltaH < 0 and deltaS < 0 for the reaction of rutin with SA. So the binding forces was mainly H-bond and Van der Waals. The effect of the drug on the conformation of serum albumin was also studied by using synchronous fluorescence spectroscopy. Rutin could be deposited and transported by serum protein in vivo. Rutin had nearly no effect on the serum protein conformation.