Probing the stability of the disulfide radical intermediate of thioredoxin using direct electrochemistry

Daniel L. Johnson, Steven W. Polyak, John C. Wallace, Lisandra L. Martin*

*Corresponding author for this work

Research output: Contribution to journalArticlepeer-review

20 Citations (Scopus)


Thioredoxin, a redox active disulfide protein, has been specifically immobilized at a modified gold electrode. The thioredoxin is uniquely oriented relative to the electrode surface via a histidine tag thereby enabling the redox mechanism of protein to be examined. When scanning the applied potential in the negative direction (cathodic), two one-electron reduction waves can be observed. The first of these redox waves occurs at -90 mV and is electrochemically reversible at all scan rates whereas the second wave occurs at -433 mV is irreversible. These two processes are interpreted as the initial reduction of the disulfide form of the protein to a stable (reversible) semi-reduced radical anion intermediate, followed by an electrochemically irreversible process to form a fully reduced thioredoxin. These electron transfer characteristics suggest that a radical intermediate retaining the sulfur-sulfur bond is thermodynamically stable but the addition of a second electron results in bond scission.

Original languageEnglish
Pages (from-to)495-500
Number of pages6
JournalLetters in Peptide Science
Issue number5-6
Publication statusPublished - Nov 2003
Externally publishedYes


  • Direct electrochemistry
  • Disulfide protein
  • Gold electrode
  • Metal affinity
  • Protein immobilization
  • Radical intermediate
  • Thioredoxin


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