Nanoplastics Intensify the Inhibitory Effect of Di‐n‐octylo‐phthalate on Trypsin: Spectroscopic and Computer Simulation Analysis

Given their frequent coexistence of plasticizers and nanoplastics, assessing their combined toxicological impacts is essential. This study investigates the interactions between di-n-octyl phthalate (DNOP) and trypsin (TRY) in the presence of polystyrene nanoplastics (PSNPs) at molecule levels. Molecular docking analysis demonstrates that DNOP could enter the active site of TRY. Spectral analyses indicate that DNOP changed TRY's conformation and residue microenvironment, which were exacerbated by the presence of PSNPs. Particle size and transmission electron microscope show that PSNPs adsorbed TRY, forming a protein corona. Enzyme activity experiments confirm that DNOP inhibited the activity of TRY, with PSNPs further enhancing this inhibitory effect. Specifically, PSNPs bind to TRY, inducing conformational changes that expose additional binding sites, while adsorbing DNOP to increase the local concentration and promote the interaction between DNOP and TRY. The findings provide novel insights when evaluating the risks associated with both PSNPs and phthalates.