Preparing the pure lignin peroxidase and exploring the effects of chemicals on the activity

Heterogous expression of lignin peroxidase (LiP) from Phanerochaete chrysosporium was performed in by E. coli prokaryotic expression system, and pure LiP was prepared by washing, refolding, and purification. The enzyme activity was measured by the resveratrol oxidation method. The effects of different chemicals on LiP activity were explored by adding different kinds of metal ions, acids/phenols, and surfactants. The optimal pH and temperature are 4.2 and 40 °C. The single-factor screening experiment showed that adding 1 mM Mn²⁺, 0.1 mM DL-lactic acid, and 2% PEG-4000 had the best promotion effect on the enzyme activity of recombinant LiP, which was 160.61%, 188.46%, and 247.83%, respectively. Further, the synergistic addition of Mn²⁺ and PEG-4000 achieved the best enzyme activity promotion effect of 277.51%. In addition, the addition of DL-lactic acid alone could promote LiP activity. However, the co-addition of lactic acid with Mn²⁺ and PEG-4000 contributed only 247.87%, which indicated that the addition of DL-lactic acid had an inhibitory effect when applied synergistically. For the first time, it was found that PEG-4000 increased LiP enzyme activity obviously and had a synergistic effect with Mn²⁺, serving as a reference for LiP in studies and applications pertaining to lignin breakdown.