Efficient catalytic removal of phenolic pollutants by laccase from Coriolopsis gallica: Binding interaction and polymerization mechanism

Abstract

Laccase is a green catalyst that can efficiently catalyze phenolic pollutants, and its catalytic efficiency is closely related to the interaction between enzyme and substrates. To investigate the binding effects between enzyme and phenolic pollutants, phenol, p-chlorophenol, and bisphenol A were used as substrates in this study. We focused on the removal and catalytic mechanism of these pollutants in water using yellow laccase derived from Coriolopsis gallica. The enzymatic catalytic products were characterized using Ultraviolet-Visible Absorption Spectroscopy (UV–Vis), Fourier Transform Infrared Spectroscopy (FTIR), and High-Resolution Mass Spectrometry (HRMS), and the catalytic mechanism of laccase on phenolic pollutants was further explored by molecular docking. Based on the structural characterization and molecular docking results, the possible polymerization pathways of these phenolic compounds were speculated. Laccase catalyzed phenol to produce phenolic hydroxyl radicals, their para-radicals, and ortho-radicals, which polymerized to form oligomers linked by benzene‑oxygen-benzene and benzene-benzene. P-chlorophenol produced phenolic hydroxyl radicals and their ortho-radicals, polymerizing to form oligomers connected by benzene‑oxygen-benzene or benzene-benzene. The CC bond of the isopropyl group of bisphenol A broke to formed an intermediate product, which was further polymerized to formed a benzene‑oxygen-benzene linked oligomer.