Probing Bioelectronic Connections Using Streptavidin Molecules with Modified Valency

Bintian Zhang, Eathen Ryan, Xu Wang, Stuart Lindsay

Research output: Contribution to journalArticlepeer-review

Abstract

As molecular electronic components, proteins are distinguished by a remarkably long electronic decay length (∼10 nm) together with high contact resistance and extreme sensitivity to the chemical details of the contact. As a consequence, the conductance of even a large bioelectronic assembly is largely controlled by the conductance of the contacts. Streptavidin is a versatile linker protein that can tether together biotinylated electrodes and biotinylated proteins but with an ambiguity about the contact geometry that arises from its four possible binding sites for biotin. Here, we use engineered streptavidin tetramers, selected to contain a defined ratio of active monomers to “dead” monomers so as to define the biotin binding sites. We find a strong dependence of conductance on the separation of the biotin molecules, consistent with a short-range tunneling interaction within the streptavidin and in contrast to the long-range transport observed inside larger proteins. Hexaglutamate tails label the active monomers, and the additional negative charge enhances conductance significantly. This effect is quantitatively accounted for by an electronic resonance in the protein conductance.

Original languageEnglish (US)
Pages (from-to)15139-15144
Number of pages6
JournalJournal of the American Chemical Society
Volume143
Issue number37
DOIs
StatePublished - Sep 22 2021

ASJC Scopus subject areas

  • Catalysis
  • Chemistry(all)
  • Biochemistry
  • Colloid and Surface Chemistry

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