Long-range electron transfer between bacterial multiheme cytochromes and hematite (001) surfaces

COLL 111

Nicholas S. Wigginton, wigginto@vt.edu, Department of Geosciences, Virginia Polytechnic Institute and State University, 4044 Derring Hall, Blacksburg, VA 24061, Kevin M. Rosso, kevin.rosso@pnl.gov, Chemical and Materials Sciences Division, Pacific Northwest National Laboratory, Richland, WA 99352, M. F. Hochella Jr., Department of Geosciences, Virginia Tech, 4044 Derring Hall, Blacksburg, VA 24061, and Andrew Gregory Stack, andrew.stack@eas.gatech.edu, School of Earth and Atmospheric Science, Georgia Institute of Technology, Atlanta, GA 30309.
Long-range electron transfer is thought to be very important, possibly even rate-limiting, at the mineral/microbe interface. We designed and carried out single-molecule tunneling spectroscopy measurements using multiheme cytochromes involved in the interfacial electron transfer step from Shewanella oneidensis. The distance-dependence of the tunneling spectra at hematite (α-Fe2O3) surfaces, as probed using electrochemical scanning tunneling microscopy (EC-STM) with insulated Au tips under a range of solution and atmospheric conditions, show decay features consistent with water participation in the tunneling process. We will report on how the spectra systematically change as a function of solution conditions, and also for when cytochromes are covalently linked to the Au tip. From previous work, we expect that the distance dependence can be strongly modified by participation of redox centers in the cytochromes. This research is aimed at providing insight into the efficiency of bacterial metal-reducing enzymes for mediating long-range electron transfer to mineral surfaces.
 

The Physical Chemistry of Environmental Interfaces
2:00 PM-5:20 PM, Monday, April 7, 2008 Morial Convention Center -- Rm. 225, Oral

Division of Colloid & Surface Chemistry

The 235th ACS National Meeting, New Orleans, LA, April 6-10, 2008