Dynamic Variation in Protein-Small Molecule Interaction Observed by   Double-Nanohole Optical Trapping
  The interaction of proteins with small molecules is fundamental to their function in living organisms and it is widely studied in drug development. Here we compare optical trapping dynamics of streptavidin and biotinylated streptavidin using a double nanohole optical trap in a metal film. Consistent and clearly distinct behavior is seen between the protein with and without the small molecule binding. The real-time dynamics at the single protein level are accessible with this technique, which also has advantages of not requiring tethering to a surface or the need for exogeneous markers. 
Ahmed Al Balushi and Reuven Gordon
physics.bio-ph