Study on Binding Competition Between Mn(II) and Zn(II) to Bovine Serum Albumin by Fluorescence Quenching Method

The binding between Mn(Ⅱ) and bovine serum albumin(BSA) was investigated by fluorescence spectrum.The binding constant,the number of binding site and thermodynamic parameters were measured at different temperatures by fluorescence quenching method.The effect of Mn(Ⅱ) on the conformation of BSA had also been analyzed using synchronous fluorescence spectroscopy and the binding mode between Mn(Ⅱ) and BSA was discussed.Experimental results showed that the number of binding site was 1,the quenching process was dynamic quenching,the binding process was mainly entropy-driven and the interaction was mainly hydrophobic force.On this basis,the binding between Mn(Ⅱ),Zn(Ⅱ) to BSA in Mn(Ⅱ)-BSA-Zn(Ⅱ) bimetallic system was investigated by fluorescence quenching method.The fluorescence quenching association formula for the bimetallic system was derived on the basis of the Stern-Volmer equation.By contrasted with the single metal system,it was suggested that Zn(Ⅱ) competed with Mn(Ⅱ) for binding BSA.