Simultaneous binding characterization of different chromium speciation to serum albumin

The binding process between three species of chromium and serum albumin (SA) was investigated, as well as the interaction between K₂Cr₂O₇ and bovine serum albumin (BSA) under coexistence of different chromium forms. CrCl₃, K₂Cr₂O₇ and Crpic bound to SA spontaneously through Van der Waals force, and their binding constants were 10³–10⁴ M⁻¹ at 298 K, respectively. K₂Cr₂O₇ and Crpic both had strong binding affinity for BSA, and significantly affected the secondary structure of BSA and the microenvironment surrounding amino acid residues. Chromium exhibited a greater fluorescence quenching constant towards HSA than toward BSA, and K₂Cr₂O₇ induced greater conformational changes in human serum albumin (HSA) than in BSA. A weak binding of CrCl₃ to BSA had no significant effect on the binding affinity of K₂Cr₂O₇ to BSA. K₂Cr₂O₇ and BSA have a greater binding affinity when coexisting with Crpic, and K₂Cr₂O₇ induces a greater conformational change in BSA.