This is a novel force generation mechanism of actomyosin.
An actin filament (F-actin) produces an electric field (black arrows) as high as 100 MV/m around F-actin due to its negative surface charges. The water molecules in such a high electric field become hyper-mobile water molecules (HMW, light green) in close proximity of F-actin. On the other hand, ATP in solution binds with a myosin head (orange) and is split into adenosine diphosphate (ADP) and inorganic phosphate (Pi) in the head. When the myosin head with ADP and Pi binds with F-actin (orange red), several actin subunits change their structures (beige). Then the electric field strength decreases around these changed actin subunits and the HMW intensity also decreases (light blue) to become close to free water.
In the present study, the protein hydration state has been found to be more stable in the stronger HMW region. In the figure, the myosin head is driven to the right where the HMW intensity is stronger (light green), with detaching from F-actin and attaching again with F-actin. The force evaluated by the present method is as high as several piconewtons, which is on the level of the experimental values. This can be a principle of novel surface force acting between a charged macromolecule, such as protein and DNA, and a solute protein widely applicable to science and technology.