Directed Evolution of a Bacterial Laccase (CueO) for Enzymatic Biofuel Cells

Escherichia coli's copper efflux oxidase (CueO) has rarely been employed in the cathodic compartment of enzymatic biofuel cells (EBFCs) due to its low redox potential (0.36 V vs. Ag/AgCl, pH 5.5) towards O2 reduction. Herein, directed evolution of CueO towards a more positive onset potential wa...

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Bibliographic Details
Published in:Angewandte Chemie International Edition 2019-03, Vol.58 (14), p.4562-4565
Main Authors: Zhang, Lingling, Cui, Haiyang, Zou, Zhi, Garakani, Tayebeh Mirzaei, Novoa‐Henriquez, Catalina, Jooyeh, Bahareh, Schwaneberg, Ulrich
Format: Article
Language:English
Subjects:
Biochemical fuel cells
Biodiesel fuels
bioelectrocatalysis
Biofuels
Biomass
Coupling (molecular)
CueO engineering
Directed evolution
E coli
Efflux
electrochemical screening
Electrochemistry
enzymatic biofuel cell
Evolution
Fuels
Laccase
Redox potential
Silver chloride
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Summary:Escherichia coli's copper efflux oxidase (CueO) has rarely been employed in the cathodic compartment of enzymatic biofuel cells (EBFCs) due to its low redox potential (0.36 V vs. Ag/AgCl, pH 5.5) towards O2 reduction. Herein, directed evolution of CueO towards a more positive onset potential was performed in an electrochemical screening system. An improved CueO variant (D439T/L502K) was obtained with a significantly increased onset potential (0.54 V), comparable to that of high‐redox‐potential fungal laccases. Upon coupling with an anodic compartment, the EBFC exhibited an open‐circuit voltage (Voc) of 0.56 V. Directed enzyme evolution by tailoring enzymes to application conditions in EBFCs has been validated and might, in combination with molecular understanding, enable future breakthroughs in EBFC performance Directed CueO evolution via electrochemical screening found that the substitutions at the second sphere of T1 Cu led to a dramatic overpotential decrease of 0.12 V, making CueO competitive to fungal laccases and applicable in enzymatic biofuel cells.
ISSN:1433-7851
1521-3773
DOI:10.1002/anie.201814069