Reduction of CCl4 to the trichloromethyl radical by lignin peroxidase H2 from Phanerochaete chrysosporium.

We were able to spin trap the trichloromethyl radical with PBN in a reaction mixture containing lignin peroxidase H2, H2O2, CCl4, veratryl alcohol and EDTA. Upon removal of CCl4, EDTA radicals were detected. Based on a previously reported study (Shah et al., 1992, J. Biol. Chem. 267, 21564-21569), we propose that the oxidation of EDTA to EDTA derived radicals is mediated by the veratryl alcohol cation radical, and the reduction of CCl4 to the trichloromethyl radical is caused by the EDTA derived radicals. The novel finding here is that CCl4, which is neither a substrate for the enzyme nor a good reductant, is degraded via free radicals generated by lignin peroxidases under reducing conditions.