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 K 2 Cr 2 O 7 and bovine serum albumin (BSA) under coexistence of different chromium forms. CrCl 3 , K 2 Cr 2 O 7 and Crpic bound to SA spontaneously through Van der Waals force, and their binding constants were 10 3 –10 4  M −1 at 298 K, respectively. K 2 Cr 2 O 7 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 K 2 Cr 2 O 7 induced greater conformational changes in human serum albumin (HSA) than in BSA. A weak binding of CrCl 3 to BSA had no significant effect on the binding affinity of K 2 Cr 2 O 7 to BSA. K 2 Cr 2 O 7 and BSA have a greater binding affinity when coexisting with Crpic, and K 2 Cr 2 O 7 induces a greater conformational change in BSA.