Direct evidence for heme-assisted solid-state electronic conduction in multi-heme c-type cytochromes

Kavita Garg, Mihir Ghosh, Tamar Eliash, Jessica H. van Wonderen, Julea N. Butt, Liang Shi, Xiuyun Jiang, Futera Zdeněk, Jochen Blumberger, Israel Pecht, Mordechai Sheves, David Cahen

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Abstract

Multi-heme cytochrome c (CytC) proteins are key for transferring electrons out of cells, to enable intracellular oxidation to proceed, also in the absence of O2. In these proteins most of the hemes are arranged in a linear array suggesting a facile path for electronic conduction. To test this, we studied solvent free electron transport across two multi-heme CytC-type: MtrF (deca-heme CytC) and STC (tetra-heme CytC). Transport is measured across monolayers of these proteins in solid state configuration between Au electrodes. Both proteins showed 1,000x higher conductance than single heme, or heme-free proteins, but similar to monolayers of conjugated organics. Conductances are found to be temperature-independent (320-80K), suggesting tunneling as the transport mechanism based on present experimental data. This mechanism is consistent with modelling the I-V curves, results of which could be interpreted by having protein-electrode coupling as rate limiting, rather than transport within the proteins.
Original languageEnglish
Pages (from-to)7304-7310
Number of pages7
JournalChemical Science
Volume9
Issue number37
Early online date27 Jul 2018
DOIs
Publication statusPublished - 7 Oct 2018

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