Long-range protein electron transfer observed at the single-molecule level: In situ mapping of redox-gated tunneling resonance

Qijin Chi, O Farver, Jens Ulstrup

Research output: Contribution to journalJournal articleResearchpeer-review

Abstract

A biomimetic long-range electron transfer (ET) system consisting of the blue copper protein azurin, a tunneling barrier bridge, and a gold single-crystal electrode was designed on the basis of molecular wiring self-assembly principles. This system is sufficiently stable and sensitive in a quasi-biological environment, suitable for detailed observations of long-range protein interfacial ET at the nanoscale and single-molecule levels. Because azurin is located at clearly identifiable fixed sites in well controlled orientation, the ET configuration parallels biological ET. The ET is nonadiabatic, and the rate constants display tunneling features with distance-decay factors of 0.83 and 0.91 angstrom(-1) in H2O and D2O, respectively. Redox-gated tunneling resonance is observed in situ at the single-molecule level by using electrochemical scanning tunneling microscopy, exhibiting an asymmetric dependence on the redox potential. Maximum resonance appears around the equilibrium redox potential of azurin with an on/off current ratio of approximate to 9. Simulation analyses, based on a two-step interfacial ET model for the scanning tunneling microscopy redox process, were performed and provide quantitative information for rational understanding of the ET mechanism
Original languageEnglish
JournalProceedings of the National Academy of Sciences of the United States of America
Volume102
Issue number45
Pages (from-to)16203-16208
ISSN0027-8424
Publication statusPublished - 2005

Fingerprint Dive into the research topics of 'Long-range protein electron transfer observed at the single-molecule level: In situ mapping of redox-gated tunneling resonance'. Together they form a unique fingerprint.

Cite this