More About Molecular Mechanics of Enzymes

Laser light can be used to perform multiple roles, including sensing, manipulating and moving objects within a laser trap (so-called optical tweezers). It is remarkable that the application of light allows one to exert minute optical forces on individual protein molecules. By pulling on individual molecules it has been possible to study DNA and protein structures in great detail. The pulling and unfolding of proteins has revealed the intramolecular forces that give them their three-dimensional structure. Optical tweezer experiments have also allowed the direct measurement of pico-Newton forces that are exerted by individual motor proteins. However, optical tweezers and other single-molecule techniques are currently not sensitive enough to resolve femto-Newton (fN) forces, and hence not all molecular forces can yet be investigated. An important, but so far poorly understood example is the minuscule fN forces that are exerted by active enzymes when they are catalysing reactions in living