MICROSCOPY Vol.45▶No.3 2010

Watching Single Molecule under Optical Microscopes

Takayuki Nishizaka and Tomoko Masaike

Abstract: Molecular linear motors in living cells, such as myosin and kinesin, play key roles to maintain life in various events, i.e., transportation of organelles, cell migration, cell division and so on. The mechanism illustrating how these motors work as a ‘molecular machine’ has been studied through biophysical approaches and well established especially at the single molecular level. The other stream to study molecular motors is to examine proteins that show continuous directed motion, such as rotation of a subunit; F1-ATPase is an extreme as the world’s smallest rotary motor with the size of 10 nm. Our approach was not only the visualization of rotational motion of the shaft, but also the simultaneous detection of a chemical reaction that drives the rotation. Techniques of our optical microscopes to detect nanometer-scale motions and their applications to molecular motors are described.

Key words: motor proteins, single molecule biophysics, F1-ATPase, total reflection fluorescence microscopy