Reactions of "hybrid" Mn-peroxidase of the white rot fungus Panus tigrinus with benzylic alcohols in the presence of mediators

"Hybrid" Mn-peroxidase (hMnP) isolated from the white rot fungus Panus tigrinus 8/18 was studied with respect to its reactions with veratryl alcohol in the presence of typical laccase mediators in the reaction mixture. Eight compounds were tested as potential mediators in this reaction and only 1-hydroxybenzotriazole (HBT) and 3-hydroxy-1,2,3-benzotriazin-4(3H)-one (HBTO) were found to be effective. Up to 99% of 1 M veratryl alcohol was oxidized with formation of veratraldehyde as a reaction product over 24 h depending on the buffer system used. Except for veratryl alcohol, anisyl alcohol but not benzyl alcohol was oxidized in this reaction. Reactions with the participance of mediators were not catalytic, and the mediators were consumed during reaction with formation of dehydroxylated derivatives. Reactions with both HBT and HBTO resulted in temporal inactivation of hMnP. Kinetics of hMnP inactivation revealed it to be a pseudo-third order reaction. Investigation of the transformation of the absorption spectra of hMnP redox cycle intermediates in the presence of HBT or HBTO showed that the most likely reason of hMnP inactivation was its interaction with non-oxidized mediators