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

Ian R. Wheeldon, Joshua W. Gallaway, Scott Calabrese Barton, Scott Banta

Research output: Contribution to journalArticle

  • 49 Citations

Abstract

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 α-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 α-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 α-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.

LanguageEnglish (US)
Pages15275-15280
Number of pages6
JournalProceedings of the National Academy of Sciences of the United States of America
Volume105
Issue number40
DOIs
StatePublished - Oct 7 2008

Profile

Hydrogels
Hydrogel
Laccase
Electrons
Osmium
Catechol Oxidase
Electrodes
Bioelectric Energy Sources
Oxygen
Protein Engineering
Leucine Zippers
Peptides
Matrix-Assisted Laser Desorption-Ionization Mass Spectrometry
Tissue Engineering
Circular Dichroism
Histidine
Oxidation-Reduction
Mass Spectrometry
Spectrum Analysis
Water

Keywords

  • Biocatalysis
  • Biofuel cell
  • Biomaterial
  • Laccase
  • Protein

ASJC Scopus subject areas

  • General

Cite this

Bioelectrocatalytic hydrogels from electron-conducting metallopolypeptides coassembled with bifunctional enzymatic building blocks. / Wheeldon, Ian R.; Gallaway, Joshua W.; Barton, Scott Calabrese; Banta, Scott.

In: Proceedings of the National Academy of Sciences of the United States of America, Vol. 105, No. 40, 07.10.2008, p. 15275-15280.

Research output: Contribution to journalArticle

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