Visualizing and manipulating individual protein molecules

Single-molecule imaging and manipulation techniques have evolved in the past decade from mere jaw-dropping attractions to essential laboratory tools. By applying single-molecule methods important insights otherwise unavailable have been obtained on various biomolecular systems. Constantly improving single-molecule imaging techniques keep expanding the scale of the explorable spatial detail, thereby providing possible solutions to getting around the debilitating diffraction limit present in physiological-condition structural investigations. In some areas, such as motor protein studies, single-molecule methods have become part of the routine and essential research toolkit. Entire research fields, such as single-molecule force spectroscopy, have been born. In the present review single-molecule visualization and manipulation methods are reviewed with a focus on proteins. Relevant signals and prominent applications are discussed along with experimental examples and recent important results. Finally, the perspectives of the single-molecule field are explored.