Voltammetry of a "protein on a rope".
A periplasmic electron-transfer protein, cytochrome c(555)(m) from Aquifex aeolicus contains a 62-residue N-terminal extension by which it is anchored to the membrane--most probably via a thioester bond to its N-terminal cysteine. This linker can act as a "rope" to tether the protein close to its reaction partners. Mimicking this principle, a recombinant cytochrome c(555)(m), expressed in Escherichia coli, has been attached covalently to a gold electrode modified with 6-mercaptohexan-1-ol. The "tethered" cytochrome c(555)(m) displays remarkably fast electron-transfer kinetics, with an electrochemical exchange rate constant k(0) of 1.4 x 10(4) s(-1). The results show that fast electron transfer is associated with weak interactions: importantly, the tethered cytochrome can explore many different orientations without escaping into solution.
Baymann
Frauke
F
Inorganic Chemistry Laboratory, South Parks Road, Oxford, UK. baymann@ibsm.cnrs-mrs.fr
Barlow
Nicola L
NL
Aubert
Corinne
C
Schoepp-Cothenet
Barbara
B
Leroy
Gisele
G
Armstrong
Fraser A
FA
D000327:Adsorption; D000595:Amino Acid Sequence; D001419:Bacteria; D001426:Bacterial Proteins / Q000737:chemistry*; D003574:Cytochrome c Group / Q000737:chemistry*; D004566:Electrodes; D004579:Electron Transport; D004926:Escherichia coli; D008969:Molecular Sequence Data; D011994:Recombinant Proteins / Q000737:chemistry
D001426:Bacterial Proteins; D003574:Cytochrome c Group; D011994:Recombinant Proteins; C018887:cytochrome c-555