Effects of several metal ions on the interactions between Ponceau 4R and bovine serum albumin——fluorescence spectroscopic study

Fluorescence spectroscopic method was adopted to study the quenching characteristics of endogenous fluorescence of bovine serum albumin(BSA)by synthetic food pigment Ponceau 4R at different temperatures(15,27and 39℃),and the effects of metal ions Cu2+,Ni 2+ and Pb2+ on the interactions between BSA and Ponceau 4R were investigated.Moreover,the quenching constant KSV,binding constant KA,and binding site n under different temperatures were measured.Results indicate that the three kinds of metal ion almost have no effect on the fluorescence quenching mechanism of BSA by Ponceau 4R.However,Cu2+,Ni2+ and Pb2+ are in some way able to combine with BSA,thereby enhancing the interactions between BSA and Ponceau 4R as well as the quenching of the endogenous fluorescence of BSA.