The effect of dichlorvos on the structural alteration of serum albumins: a combined spectroscopic and molecular dynamic simulation approach

The formation of a complex between a protein and a pesticide critically affects the absorption, distribution, metabolism, and toxicity of the pesticide. Therefore, the study of the protein-pesticide binding is very important in toxicology. In this work, the interactions between dichlorvos with human serum albumin (HSA) and bovine serum albumin (BSA) have been investigated by UV absorption spectroscopy, fluorescence spectroscopy, molecular docking, and molecular dynamic simulation. The fluorescence intensity of HSA and BSA decreased by the addition of dichlorvos. Dichlorvos can quench the intrinsic fluorescence of HSA/BSA by static quenching and non-radiative energy transferring. The binding constants of dichlorvos with HSA and BSA at 298 K were calculated as (3.62 +/- 0.01) x 10(3) and (2.12 +/- 0.01) x 10(4) dm(3) mol(-1). The distances, r, between the donor (HSA/BSA) and the acceptor (dichlorvos) evaluated according to fluorescence resonance energy transfer, were 5.64 and 5.98 nm. Molecular docking studies revealed dichlorvos can bind to site 1 of HSA/BSA. In addition, 14 ns MD simulation was performed and the results suggested that the binding of dichlorvos could cause changes in the secondary and tertiary structures of HSA and BSA.