Determination of thiram by a peptide-Cu mimetic enzyme with peroxidase-like activity

In this study, we constructed a peptide‑copper (peptide-Cu) mimetic enzyme for thiram detection. The enzyme mimics peroxidase-like activity (POD), which allows it to catalyze the oxidation of o-phenylenediamine (OPD) substrates in the presence of hydrogen peroxide (H₂O₂). Thiram can prevent the catalytic activity of peptide-Cu mimetic enzymes by surface blocking, inhibiting chromogenic substrate oxidation and facilitating the rapid detection of thiram. The inhibitory mechanism was elucidated through molecular dynamics (MD) simulations and density functional theory (DFT) calculations, revealing that thiram synergistically reduces the catalytic activity of the peptide-Cu mimetic enzyme by disrupting its structural stability and electronic properties. Thiram exhibited good linearity in the concentration range from 0.01 to 5 μg/mL, with a lowest limit of detection (LOD) of 0.048 μg/mL, and showed a good recovery range from 79.71% to 108.13% in real samples. This approach, based on peptide-metal complexes, offers a straightforward and affordable method for pesticide monitoring.