Force generation in muscle during contraction arises from direct interaction of the two main protein components of the muscle,
myosin and actin. The process is driven by the energy liberated from the hydrolysis of ATP. In the presence of CaATP the energy
released from hydrolysis produces conformational changes in myosin and actin, which can be manifested as an internal motion
of myosin head while bound to actin. It is suggested that myosin heads attached to actin produce conformational changes during
the hydrolysis process of ATP, which results in a strain in the head portion of myosin in an ATP-dependent manner. These structural
changes lead to a large rotation of myosin neck region relieving the strain.
Paramagnetic probes and EPR spectroscopy provide direct method in which the rotation and orientation of specifically labelled
proteins can be followed during muscle activity. In order to find correlation between local and global structural changes
in the intermediate states of the ATPase cycle, the spectroscopic measurements were combined with DSC measurements that report
domain stability and interactions.
In the review a detailed description of the application of EPR and DSC techniques in muscle protein research will be given.
The measurements show that the small local structural changes detected by EPR after nucleotide binding influence the global
structure of protein system responsible for muscle contraction.