ORIGINAL PAPER The effect of dichlorvos on the structural alteration of serum albumins: a combined spectroscopic and molecular dynamic simulation approach Tecush Mohammadi 1 • Yousef Ghayeb 1 • Tayebeh Sharifi 1 • Taghi Khayamian 1 Received: 21 July 2016 / Accepted: 10 October 2016 Ó Springer-Verlag Wien 2016 Abstract The formation of a complex between a protein and a pesticide critically affects the absorption, distribu- tion, 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) 9 10 3 and (2.12 ± 0.01) 9 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 ter- tiary structures of HSA and BSA. Graphical abstract Keywords Fluorescence quenching  Absorption spectroscopy  Serum albumin  Dichlorvos  Molecular docking  Molecular dynamics simulation Introduction Organophosphate pesticides (OPs) are extensively used to control various insects on crops [1, 2]. Dichlorvos (Scheme 1) is a relatively volatile organophosphate insec- ticide used widely to control insects, primarily in storage areas, barns, workplaces, and homes [3, 4]. Dichlorvos is taken into the body very rapidly by different routes (lungs, stomach, or skin). Upon entering the bloodstream, dichlorvos is carried to all the organs to interact with dif- ferent targets. Like all organophosphates, dichlorvos exerts its toxic effects, in part, by inactivating a critical nervous system enzyme, acetylcholine esterase. However, dichlorvos can bind to other proteins, such as albumin. Nevertheless, the role of dichlorvos in toxicity is not well defined [2, 4–10]. Knowledge of dichlorvos binding to serum albumin (SA), the major plasma protein, which has a potential to be a new biomarker of organophosphate exposure, is beneficial to & Yousef Ghayeb ghayeb@cc.iut.ac.ir 1 Department of Chemistry, Isfahan University of Technology, 84156-83111 Isfahan, Iran 123 Monatsh Chem DOI 10.1007/s00706-016-1857-9