The influence of Cd²⁺, Hg²⁺ and Pb²⁺ on taxifolin binding to bovine serum albumin by spectroscopic methods: with the viewpoint of toxic ions/drug interference.

The effect of heavy metal ions, Cd(2+), Hg(2+) and Pb(2+) on taxifolin binding to bovine serum albumin (BSA) has been investigated by spectroscopic methods. The results indicated that the presence of heavy metal ions significantly affected the binding modes and binding affinities of taxifolin to BSA, and the effects depended on the type of heavy metal ions. One binding mode was found for taxifolin with and without Cd(2+), while two binding modes-a weaker one at low concentration and a stronger one at high concentration-were found for taxifolin in the presence of Hg(2+) and Pb(2+). Cd(2+) decreased the binding affinity of taxifolin for BSA by 7.3%; however, Hg(2+) increased the binding affinity of taxifolin for BSA by 13.3% in lower concentration and 33.3% in higher concentration. Pb(2+) decreased the binding affinity of taxifolin for BSA by 28.4% in lower concentration, and increased the binding affinity of taxifolin for BSA by 20.6% in higher concentration. The decreased binding affinity of taxifolin for BSA in the presence of Cd(2+) was mainly because of the existence of competitive binding between taxifolin and Cd(2+). However, the conformational change of BSA may the main reason for the changed binding affinity and binding distance of taxifolin for BSA in the presence of Hg(2+) and Pb(2+).