The effect of Cu2+ or Fe3+ on the noncovalent binding of rutin with bovine serum albumin by spectroscopic analysis

The interaction of rutin to bovine serum albumin (BSA) in aqueous solution was investigated by fluorescence spectra and ultraviolet–visible (UV–vis) spectra at pH 7.40. There are also some metal ions present in blood plasma, thus the research about the effect of metal ions on the interaction of drugs with proteins is crucial. Therefore, we have studied the effect of Cu2+ or Fe3+ on the interaction between rutin and BSA by using spectroscopic technique at pH 7.40, for the first time. The results of fluorescence titration indicated that rutin could quench the intrinsic fluorescence of BSA in a static quenching way. The binding sites number (n), the binding constant (K) and the spatial-distance (r) of rutin with BSA without or with Cu2+ or Fe3+ at 310 K were calculated. The result showed that the presence of Cu2+ or Fe3+ increased the binding constant and changed the binding distance between the acceptor and the donor, which possibly results from the formation of metal ions–BSA complex. The effect of rutin on the conformation of BSA was also analyzed using UV under experimental conditions. Furthermore, the fluorescence displacement experiments indicated that rutin is situated within subdomain IIA of BSA.