Simultaneous binding characterization of different chromium speciation to serum albumin

Abstract

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.