Dehalogenation activity of a miniaturized peroxidase: substrate dependent functional switch

Area of Science:

• Biocatalysis
• Environmental Chemistry
• Enzyme Mimics

Background:

• Natural peroxidases interact with 4-halophenols as substrates or inhibitors.
• Heme-enzyme mimics offer tunable catalytic properties.
• Halophenols are common environmental pollutants requiring effective remediation strategies.

Purpose of the Study:

• To investigate the dual role of Fe-mimochrome VI*a (Fe-MC6*a) in processing 4-halophenols.
• To elucidate the mechanistic basis for chemo-divergent reactions (dehalogenation vs. oligomerization).
• To assess Fe-MC6*a's efficacy as a bioremediation catalyst for mixed halophenol waste streams.

Main Methods:

• Spin-trapping studies and Electron Paramagnetic Resonance (EPR) analysis.
• Chemo- and regio-selective oxidation assays with various 4-halophenols (e.g., 4-chlorophenol, 4-fluorophenol).
• Competitive inhibition assays using 2,4,6-trichlorophenol and mixed halophenol substrates.

Main Results:

• Fe-MC6*a selectively catalyzes dehalogenation of 4-chlorophenol and oligomerization of 4-fluorophenol.
• Mechanistic insights into the chemo-divergent outcomes were proposed.
• 4-halophenols competitively inhibited Fe-MC6*a but did not lead to complete catalyst inactivation.
• Fe-MC6*a demonstrated resilience and turnover in complex substrate mixtures.

Conclusions:

• Fe-MC6*a functions as a versatile catalyst, processing halophenols as substrates and exhibiting inhibitory properties.
• The catalyst's ability to handle mixed halophenol waste streams makes it a promising candidate for wastewater bioremediation.
• Fe-MC6*a offers a novel approach for simultaneous halophenol detoxification.