An experimental and theoretical study of Coprinus cinereus peroxidase-catalyzed biodegradation of isoelectronic to dioxin recalcitrants

Isoelectronic to dibenzo-p-dioxin (DBD) compounds (ID) containing nitrogen and/or sulfur atom instead of oxygen atom can be oxidized in the presence of fungal peroxidase. To elucidate the structure/activity relationship the redox potential of IDʹs was determined and correlated with calculated properties from ab initio calculations. The redox potential of IDʹs varied between 0.16 and 1.46 V versus standard calomel electrode (SCE) in acetonitrile. Spectral measurements and ab initio quantum chemical calculations showed that the redox potential correlated with the quantity of heteroatom conjugation with the 6π-aromatic system. The reactivity of IDʹs decreased if the redox potential of IDʹs increased. The calculations of docking and molecular dynamics revealed that all IDʹs may form the stable complexes in the active center of peroxidase. The acquired results permitted to conclude that low reactivity of IDʹs and their halogenated derivatives is associated with the high redox potential of recalcitrants.