Transformation of biphenyl intermediate metabolite by manganese peroxidase from a white rot fungus SQ01

Abstract:

[Objective] To understand the biochemical role of white rot fungus Trametes sp. SQ01 manganese peroxidase (MnP) towards 2-hydroxy-6-oxo-6-phenylhexa-2,4-dienoates (HOPDA)/HOPDA derivatives and to reveal the new catalytic features of MnP, white rot fungus Trametes sp. SQ01 MnP was extracted, and the purified enzymes were used in the oxidation of HOPDAs. [Methods] UV-vis spectrophotometry was used to study the transformation of 10 substituted HOPDAs by manganese peroxidase and measure the steady-state kinetics parameters of manganese peroxidase against parts of HOPDAs. The molecular structures of HOPDA and HOPDA oxidation product were analyzed by infrared spectroscopy. [Results] Manganese peroxidase exhibited catalytic activity towards both HOPDA and halogenated HOPDA. Especially, our manganese peroxidase used 3,8,11-3Cl HOPDA as substrate, while biphenyl hydrolase (2-hydroxy-6-oxo-6-phenylhexa-2,4-dienoate hydrolase) and Rhodococcus sp. R04 showed negligible activity towards this substrate. The steady-state kinetic analysis indicated that HOPDA displayed the lowest K_m among 5 HOPDAs, the catalytic efficiency (K_cat/K_m) of 3, 10-2F HOPDA was the highest. UV-visible spectroscopy analysis indicated that the maximum absorption of products of HOPDA showed blue-shift with increasing the reaction time in the visible region. Infrared analysis showed that MnP converted conjugated diene of HOPDA to monoethylenically, and cause hydroxyl on C_β to disappear. [Conclusion] Manganese peroxidase can effectively degrade HOPDA and its derivatives. Such catalytic properties of manganese peroxidase provide a new strategy for successfully degrading biphenyl and its intermediate metabolites.