Study on the interaction of herbicide paraquat with Human Serum Albumin (HSA) by spectroscopic and molecular docking techniques

Abstract

Study on the interaction of herbicide paraquat with Human Albumin Serum (HSA) by spectroscopic and molecular docking techniques Introduction: One of the strongest herbicides to eliminate weeds in agriculture is paraquat which poisoning with can be fatal. Distribution, free concentration, and metabolism of different toxins depend on how they bind to serum albumin and the three-dimensional structure of the protein binding site. Paraquat-bound and rational administration of albumin can prevent toxic and lethal effects in these patients. Aim: Since the interaction of paraquat toxin with HSA and its pharmacokinetic parameters have not been investigated, in this study, the procedure, type and location of paraquat toxin binding to human albumin serum were investigated. Material and Methods: First, the fluorescence and infrared spectra of paraquat in tris buffer were obtained by spectrofluorimetry at 278 nm excitation wavelength and 280-500 nm emission, and the paraquat spectrum was plotted with human serum albumin at different concentrations of toxin at three temperatures. Using Stern-Valmer's relation, the parameters of protein and toxin interaction were analyzed, and their interaction was investigated with Auto Dock tools software. Results: Spectroscopic studies showed that the interaction between albumin and paraquat resulted in an increase in the emission or, in other words, a dynamic type quenching occures. Also, the changes in FT-IR peaks obtained from the albumin structure in the presence of the ligand indicate an interaction between them. Molecular docking results also showed that hydrophobic bonding is the major force involved in the interaction. Fluorimetric studies in the presence of site markers also indicate overlap between the paraquat binding site at the IA site. Conclusion: Based on the results, paraquat binds at the IA site of human albumin via hydrophobic bonding, quenching mechanism occures as a result of changes in the structure of albumin and paraquat.