Exploration of Possible Degradation Pathway of Phenoxy-Radical Lignin

• 1、School of Life Sciences & Biotechnology, State Key Laboratory of Microbial Metabolism, Shanghai Jiao Tong University, Shanghai, 200240

Abstract：Lignin is an aromatic polymer that widely exists in plant cell walls, and is important in energy and material applications. Laccase is able to activate lignin by transforming phenol groups to phenoxy radical. However, the following-up degradating pathway remains unknown. In this work, we have analyzed the trajectories of phenoxy-radical lignin generated with the Reax force field, and statistically explored variations in bond length of each type of chemical bond. As a result, guaiacyl 3-O ether bonds, β-O-4 ether bonds,α-O-4 ether bonds, and 4-O-5 ether bonds exhibit a relatively high tendency in bond elongation. We further calculated energetics of the possible degradations with the density functional theory at the level of (U)B3LYP/6-311+G(d,p)//6-31G(d). Our study show that diradical pathway might be essential for laccase-initiated lignin decomposition.

Keywords： lignin ReaxFF radical decomposition quantum chemistry