Oxygen-reducing enzyme cathodes produced from SLAC, a small laccase from Streptomyces coelicolor

Gallaway, Joshua W.; Wheeldon, Ian; Rincón, Rosalba A.; Atanassov, Plamen; Banta, Scott; Barton, Scott Calabrese

doi:10.1016/j.bios.2007.11.004

Cited by 114 publications

(79 citation statements)

References 35 publications

(45 reference statements)

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“…However, a PVI-Os redox polymer-SLAC hydrogel can initially achieve 1.5 mA⅐cm Ϫ2 at pH 7.0 and 40°C (29). A similar system with a fungal laccase from Trametes versicolor reaches 0.2 mA⅐cm Ϫ2 under similar conditions (29). Milliampere per cm 2 current densities have also been demonstrated with bilirubin oxidase from Trachyderma tsunodae immobilized in a PVI-Os redox polymer on high-surface-area carbon cloth (31).…”

Section: Resultsmentioning

confidence: 99%

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Bioelectrocatalytic hydrogels from electron-conducting metallopolypeptides coassembled with bifunctional enzymatic building blocks

Wheeldon

Gallaway

Barton

et al. 2008

Proc. Natl. Acad. Sci. U.S.A.

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Here, we present two bifunctional protein building blocks that coassemble to form a bioelectrocatalytic hydrogel that catalyzes the reduction of dioxygen to water. One building block, a metallopolypeptide based on a previously designed triblock polypeptide, is electron-conducting. A second building block is a chimera of artificial ␣-helical leucine zipper and random coil domains fused to a polyphenol oxidase, small laccase (SLAC). The metallopolypeptide has a helix-random-helix secondary structure and forms a hydrogel via tetrameric coiled coils. The helical and random domains are identical to those fused to the polyphenol oxidase. Electron-conducting functionality is derived from the divalent attachment of an osmium bis-bipyrdine complex to histidine residues within the peptide. Attachment of the osmium moiety is demonstrated by mass spectroscopy (MS-MALDI-TOF) and cyclic voltammetry. The structure and function of the ␣-helical domains are confirmed by circular dichroism spectroscopy and by rheological measurements. The metallopolypeptide shows the ability to make electrical contact to a solid-state electrode and to the redox centers of modified SLAC. Neat samples of the modified SLAC form hydrogels, indicating that the fused ␣-helical domain functions as a physical cross-linker. The fusion does not disrupt dimer formation, a necessity for catalytic activity. Mixtures of the two building blocks coassemble to form a continuous supramolecular hydrogel that, when polarized, generates a catalytic current in the presence of oxygen. The specific application of the system is a biofuel cell cathode, but this protein-engineering approach to advanced functional hydrogel design is general and broadly applicable to biocatalytic, biosensing, and tissue-engineering applications.biocatalysis ͉ biofuel cell ͉ biomaterial ͉ laccase ͉ protein P rotein engineering provides the tool set to design and produce peptides and proteins that form the building blocks of new bio-inspired materials. The tool set allows for the manipulation of natural and artificial DNA sequences encoding the peptides or proteins of interest, and the subsequent biological production of the translated products. The methodology is powerful in that it allows for exact control over the identity and sequence of each residue and, consequently, the structural folding patterns of the resultant peptides or proteins (1). And, just as function stems from structure, it is also controlled within the protein-engineering scheme of materials design. There are a number of successful examples of hydrogels designed for tissueengineering and drug-delivery applications that use functional protein domains to obtain structural responsiveness to environmental cues (2-4). These examples include responsiveness to pH (5), temperature (6), shear stress (7), and ligand binding (8, 9) among others (refs. 2 and 10; ref. 3 and references therein). A wider range of applications, such as bioelectrocatalysis and biosensing, will benefit from the advantages of protein-based materials design pr...

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Section: Resultsmentioning

confidence: 99%

“…SLAC is active at pH 7.0, but with a pI of 8.4 (22) it is polycationic and therefore not matched to synthetic redox hydrogel systems operating at neutral pH (29). However, a PVI-Os redox polymer-SLAC hydrogel can initially achieve 1.5 mA⅐cm Ϫ2 at pH 7.0 and 40°C (29).…”

Section: Resultsmentioning

confidence: 99%

Bioelectrocatalytic hydrogels from electron-conducting metallopolypeptides coassembled with bifunctional enzymatic building blocks

Wheeldon

Gallaway

Barton

et al. 2008

Proc. Natl. Acad. Sci. U.S.A.

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“…Only a single study of the oxygen reduction catalysis by ScL seems to have been reported. 40 This study involved direct ET between the enzyme and a carbon nanotube modified electrode. No previous studies of the catalytic action of the other two laccases have been reported.…”

Section: Introductionmentioning

confidence: 99%

Voltammetry and Single-Molecule in Situ Scanning Tunneling Microscopy of Laccases and Bilirubin Oxidase in Electrocatalytic Dioxygen Reduction on Au(111) Single-Crystal Electrodes

et al. 2011

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“…Different methods have been devised to attain DET and establish electrical contact between the redox center and the electrode. These methods include covalent crosslinking of enzymes to the support, modifi cation of enzyme structures, [ 7,8 ] and molecular tethering. [9][10][11][12][13] Among these methods, laccase tethered with multiwalled carbon nanotubes (MWNT) exhibited very high DET for the oxygen reduction reaction (ORR), as demonstrated previously.…”

Section: Introductionmentioning

confidence: 99%

Three Dimensional Carbon Nanosheets as a Novel Catalyst Support for Enzymatic Bioelectrodes

Umasankar

Brooks

Brown

et al. 2013

Advanced Energy Materials

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A high performance laccase‐based biofuel cell cathode is developed using carbon nanosheets (CNS) as the catalyst support and buckypaper (BP) as the substrate electrode. Compared to multiwalled carbon nanotube (MWNT)‐based electrodes, CNS‐based electrodes exhibit better electrochemical properties for the oxygen reduction reaction (ORR) under biologically relevant conditions. It is shown that CNSs are conformally coated on the nanotubule bundles within the BP and that laccase is intimately attached to the CNS‐BP. Electrochemical characterization is carried out to derive the kinetic parameters of the ORR at the laccase‐CNS‐BP cathode. The laccase‐CNS‐BP exhibits a steep ORR cathodic wave with a Tafel slope of 19 mV decade‐1. The onset potential obtained for laccase ORR at CNS‐BP is 20 mV higher than that of the MWNT‐based electrodes, and the laccase‐CNS‐BP cathode has a higher current density than MWNT electrodes.

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Oxygen-reducing enzyme cathodes produced from SLAC, a small laccase from Streptomyces coelicolor

Cited by 114 publications

References 35 publications

Bioelectrocatalytic hydrogels from electron-conducting metallopolypeptides coassembled with bifunctional enzymatic building blocks

Bioelectrocatalytic hydrogels from electron-conducting metallopolypeptides coassembled with bifunctional enzymatic building blocks

Voltammetry and Single-Molecule in Situ Scanning Tunneling Microscopy of Laccases and Bilirubin Oxidase in Electrocatalytic Dioxygen Reduction on Au(111) Single-Crystal Electrodes

Three Dimensional Carbon Nanosheets as a Novel Catalyst Support for Enzymatic Bioelectrodes

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