Protein electronic conductors: hemin-substrate bonding dictates transport mechanism and efficiency across myoglobin.
Electron transport (ETp) across met-myoglobin (m-Mb), as measured in a solid-state-like configuration between two electronic contacts, increases by up to 20 fold if Mb is covalently bound to one of the contacts, a Si electrode, in an oriented manner by its hemin (ferric) group, rather than in a non-oriented manner. Oriented binding of Mb is achieved by covalently binding hemin molecules to form a monolayer on the Si electrode, followed by reconstitution with apo-Mb. We found that the ETp temperature dependence (>120 K) of non-oriented m-Mb virtually disappears when bound in an oriented manner by the hemin group. Our results highlight that combining direct chemical coupling of the protein to one of the electrodes with uniform protein orientation strongly improves the efficiency of ET across the protein. We hypothesize that the behavior of reconstituted m-Mb is due to both strong protein-substrate electronic coupling (which is likely greater than in non-oriented m-Mb) and direct access to a highly efficient transport path provided by the hemin group in this configuration.
Department of Materials and Interfaces, Weizmann Institute of Science, Rehovot 76100 (Israel).|Department of Organic Chemistry, Weizmann Institute of Science, Rehovot 76100 (Israel).
Sara
S
Raichlin
Department of Immunology, Weizmann Institute of Science, Rehovot 76100 (Israel). israel.pecht@weizmann.ac.il.
Israel
I
Pecht
Department of Organic Chemistry, Weizmann Institute of Science, Rehovot 76100 (Israel). mudi.sheves@weizmann.ac.il.
Mordechai
M
Sheves
Department of Materials and Interfaces, Weizmann Institute of Science, Rehovot 76100 (Israel). David.Cahen@weizmann.ac.il.
David
D
Cahen
D000577:Amides / Q000737:chemistry; D001059:Apoproteins / Q000737:chemistry*; D004553:Electric Conductivity; D004566:Electrodes; D006427:Hemin / Q000737:chemistry*; D008786:Metmyoglobin / Q000737:chemistry*; D008958:Models, Molecular; D015394:Molecular Structure; D009211:Myoglobin / Q000737:chemistry*
D000577:Amides; D001059:Apoproteins; D009211:Myoglobin; C010857:apomyoglobin; D008786:Metmyoglobin; D006427:Hemin
bioelectronics; electron transport; molecular junctions; myoglobin