Characterization of binding interaction of triclosan and trypsin

Triclosan (TCS), a broad-spectrum antibacterial agent, exhibits a high exposure in the environment. However, the residual TCS in the environment poses a potential risk to human health. In this study, spectroscopic methods, molecular docking and animal experiment were conducted to completely understand the interaction between trypsin and TCS. The formation of the TCS-trypsin complex was spontaneously achieved through hydrogen bonds and Van der Waals forces with a binding constant ( K a ) between 10 3 and 10 4  L mol −1 . In addition, the trypsin activity in fish intestine was inhibited by TCS exposure, revealing the potentially negative effects of TCS on metabolism. The results might be explained by changes in the conformation of the trypsin, inducing the content of unordered coil increasing significantly (from 36.2% to over 80%). This work provides useful information for assessing the toxicity of TCS at the molecular level.