Probing the molecular toxic mechanism of di-(2-ethylhexyl) phthalate with glutathione transferase Phi8 from Arabidopsis thaliana

As the most widely used plasticizer, di-(2-ethylhexyl) phthalate (DEHP) has been extensively applied to agriculture. However, its excessive accumulation may cause the active oxygen damage in plants and further lead to the destruction of antioxidant enzymes. As a core component of the glutathione antioxidant enzyme system, glutathione S-transferases (GSTs) have been reported as biomarkers for assessing oxidative damage induced by environmental pollutants, but the underlying toxic molecular mechanism has rarely been exploited. In this article, the interaction mechanism of Arabidopsis thaliana glutathione S-transferase AtGSTF8 and plasticizer DEHP was investigated at the molecular level by multispectral methods. The enzyme activity changes of AtGSTF8 upon binding with DEHP were also evaluated. A single binding site of AtGSTF8 towards DEHP was predicted and the binding force was presumed mainly by Van der Waals' force and hydrogen bonding based on static quenching mechanism. Besides, the deconstructions of the protein skeleton were also deduced based on the multispectral results and the hazardous effects of DEHP on plants growth were further demonstrated. This work will help to clarify the functional mechanism between the plasticizer DEHP and the antioxidant enzyme AtGSTF8 at the molecular level, and providing useful information for further study of the toxic effects of DEHP on plant antioxidant systems. (C) 2019 Published by Elsevier B.V.