Coupling between chemical and mechanical events and conformation of single protein molecules.

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Actin and myosin interact and undergo a sliding movement, achieving muscle contraction and other cell motility in a living organism. For this mechanical activity the energy is derived from ATP hydrolysis. Biochemical studies have shown that there are a series of chemical reactions or states that make up the overall ATP hydrolysis scheme (Lymn and Taylor 1971). The basic chemical process includes ATP binding to myosin, hydrolysis of ATP to ADP and Pi, and the dissociation of Pi and ADP from myosin. Depending on the chemical state, the interaction of myosin with actin changes (Eisenberg et al. 1980). Binding of ATP to myosin weakens the interaction with actin and the release of Pi and ADP strengthen the interaction. Both X-ray and optical diffraction studies have suggested structural changes of myosin and actin, depending on the state of the actomyosin ATPase (Huxley 1969). Recently, crystallography combined with mutagenesis has suggested structural changes in the myosin molecule (Rayment et al. 1993; Dominguez et al. 1998). These studies have tempted investigators to link one chemical state with the unique structure of myosin, which in turn determines the interaction with actin and the mechanical events in a sequential manner. The hypothesis of 1:1 coupling among these events seems simple. However, this coupling must be tested experimentally.KeywordsActin FilamentFluorescence Resonance Energy TransferMyosin HeadMyosin FilamentMyosin MoleculeThese keywords were added by machine and not by the authors. This process is experimental and the keywords may be updated as the learning algorithm improves.