Study On The Interaction Of Chloroform And Metal Ions With Proteins

The interaction between chloroform (CHCl₃) and bio-macromolecules—proteins, bovine serum albumin(BSA) , gamma seroglobulinum humanum (GSH) , and the interaction between CHCl₃ and Tryptophan (Trp) and Tyrosine (Tyr)were studied using fluorescence spectroscopy in this paper. The experimental results showed that the fluorescence quenching of BSA induced by CHCl₃ follows static quenching procedure, and the fluorescence quenching of GSH and Trp induced by CHCl₃ maybe follow static quenching procedure but still needs further study. The binding constant between CHCl₃ and BSA is far greater than that between CHCl₃ and GSH, possibly caused by differences in the structure of the two proteins.To better understand the interaction between CHCl₃ and proteins under the influences of metal ions existed in blood or in drinking water, this article also studied the interaction between metal ions (Cu²⁺, Fe³⁺ ) and BSA, GSH, and Trp. Results showed that at least two types of binding position exist between Cu²⁺ and BSA. The first binding position is not bided directly to Trp in the protein and its binding constant is smaller than that of the second. The second binding position, similar to Fe³⁺, is bided directly to Trp in the protein. Based on calculation, the result has been obtained that the binding constants of Cu²⁺ to these two proteins are smaller than that of the Fe³⁺, while to the opposite, the binding constant of Cu²⁺ to Trp is larger than that of the Fe³⁺.The ternary interaction of metal ions-proteins-CHCl₃ was also determined in this article. Results showed that metal ions slightly reduce the binding constant between CHCl₃ and BSA while strongly compete against or displace CHCl₃ to combine with GSH. The binding constants between metal ions and BSA are decreased when the concentration of CHCl₃ is increased especially when metal ions concentrations are low. On the other hand, the influence of CHCl₃ on the binding constant between metal ions andGSH is small, which further proved that the interaction between CHC13 and GSH is weaker than that between CHC13 and BSA.