The primary objective of the proposal is to develop methods for reliably imaging protein molecules to high resolution by Scanning Tunneling Microscopy and/or Atomic Force Microscopy. Previous experience with molecules of non-biological origin suggests that STM imaging of biological molecules can be done with high resolution and high reliability if a) the sample molecules are thin enough to allow electron tunneling across their widths, and b) the molecules are well anchored to an appropriate substrate surface. It is planned to use a small peptide fragment (acetyl transforming growth factor-alpha, residues 34-43) to develop methods for depositing biomolecules to clean, single crystal gold surfaces by either a) thiol binding to gold, or b) electrochemical deposition. The peptide chosen is particularly well suited to this approach because 1) it is small and thin enough to allow electron tunneling for STM imaging, 2) it has thiol-bearing cysteine residues at either end, and 3) it has two ionizable residues near the ends by which it can be electrophoretically pulled to the surface. Once the STM imaging of this small peptide has been worked out it should be possible to use the same methods to image many related peptides. Finally, by attaching thiol or disulfide containing groups to larger proteins, and imaging by AFM instead of STM, similar deposition methods should allow imaging of proteins of any size and composition.
NIH ExPorter
NIH ExPorter