Molecular basis of laccase bound to lignin: insight from comparative studies on the interaction of Trametes versicolor laccase with various lignin model compounds

Laccase, a type of multicopper oxidase, is capable of efficiently degrading lignin. Until now, the molecular basis of laccase interacting with lignin is still poorly understood. Here, five lignin model compounds (2,6-dimethoxyphenol, ferulic acid, guaiacol, sinapic acid and vanillyl alcohol) were selected to demonstrate the key binding mechanisms between Trametes versicolor laccase and lignin. The results showed that the interaction energies of the lignin model compounds with laccase varied widely, which suggested the different molecular efficiencies of laccase in degrading various components of lignin. This was in full agreement with experimental reports. Hydrophobic interactions seemed to be necessary to the interaction of the lignin/lignin model compounds with laccase, while H-bonds were not essential. The molecular basis revealed by this study was helpful in designing highly efficient laccases against lignin waste to achieve environmental protection.