Biointeractions of Herbicide Atrazine with Human Serum Albumin: UV-Vis, Fluorescence and Circular Dichroism Approaches.

Meiqing Zhu,Jie Ding,Yi Wang,Zhen Wang,Jie Zhou,Lijun Wang,Yu Wang,Shisuo Fan,Yue Xin,Wei Li

doi:10.3390/ijerph15010116

Meiqing Zhu, Jie Ding + Show 8 more

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https://doi.org/10.3390/ijerph15010116

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Abstract

The herbicide atrazine is widely used across the globe, which is a great concern. To investigate its potential toxicity in the human body, human serum albumin (HSA) was selected as a model protein. The interaction between atrazine and HSA was investigated using steady-state fluorescence spectroscopy, synchronous fluorescence spectroscopy, UV-Vis spectroscopy, three-dimensional (3D) fluorescence spectroscopy and circular dichroism (CD) spectroscopy. The intrinsic fluorescence of HSA was quenched by the atrazine through a static quenching mechanism. Fluorescence spectra at two excitation wavelengths (280 and 295 nm) showed that the fluorescence quenched in HSA was mainly contributed to by tryptophan residues. In addition, the atrazine bound to HSA, which induced changes in the conformation and secondary structure of HSA and caused an energy transfer. Thermodynamic parameters revealed that this binding is spontaneous. Moreover, electrostatic interactions play a major role in the combination of atrazine and HSA. One atrazine molecule can only bind to one HSA molecule to form a complex, and the atrazine molecule is bound at site II (subdomain IIIA) of HSA. This study furthers the understanding of the potential effects posed by atrazine on humans at the molecular level.

Highlights

Atrazine (ATR) is a triazine herbicide with an excellent herbicidal activity
Phe fluorescence is not often observed, so Trp and Tyr are commonly used as endogenous human serum albumin (HSA) fluorescent probes
Compared to the results of excitation at 280 nm and excitation at 295 nm, the fluorescence intensity of the Trp groups is more pronounced than the Tyr groups that are present in HSA, indicating that Trp is mainly involved in the quenching of HSA

Summary

Introduction

Atrazine (ATR) is a triazine herbicide with an excellent herbicidal activity. ATR can kill a broad spectrum of plants and has been widely used to control broadleaf and grass weeds in past decades [1,2,3]. ATR plays a key role in inhibiting the photosynthesis of plants by targeting the D1 protein of photosystem II (PSII) and causes the death of weeds to achieve the function of weed prevention and treatment [4,5,6,7,8]. Such herbicides have played a significant role in agriculture but can enter surface waters through various paths and can further enter groundwater [9,10,11]. The use of ATR, simazine, prometryn, and terbutryn, as four classic types of triazine herbicides, has been limited by the European Parliament

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