Scanning tunneling microscopy of uncoated recA-DNA complexes

Uncoated recA-DNA complexes were imaged with the scanning tunneling microscope (STM). The images, which reveal the right-handed helical structure of the complexes with subunits clearly resolved, are comparable in quality to STM images of metal-coated specimens. Possible conduction mechanisms that allow STM imaging of biological macromolecules are discussed.