Glutathione-mediated mineralization of C-14-labeled 2-amino-4,6-dinitrotoluene by manganese-dependent peroxidase H5 from the white-rot fungus Phanerochaete chrysosporium

Manganese-dependent peroxidase (MnP) H5 from the white-rot fungus Phaneroch aete chrysosporium, in the presence of either Mn(II)(10 mM) or GSH (10 mM), was able to mineralize C-14-U-ring-labeled 2-amino-4,6-dinitrotoluene (2-A -4,6-DNT) up to 29% in 12 days. When both Mn(II) and GSH were present, the mineralization extent reached 82%. On the other hand, no significant minera lization was observed in the absence of both Mn(II) and GSH, suggesting the requirement of a mediator [either Mn(II) or GSH] for the degradation of 2- A-4,6-DNT by MnP. Using electron spin resonance (ESR) techniques, it was fo und that the glutathionyl free radical (GS(.)) was produced through the oxi dation of GSH by MnP in the presence as well as in the absence of Mn(II). G S . was also generated through the direct oxidation of GSH by Mn(III). Our results strongly suggest the involvement of GS . in the GSH-mediated minera lization of 2-A-4,6-DNT by MnP.