Figure 13.

Schematic presentations of reaction pathways and energetic events included in the cross-bridge cycle. The cross-bridge cycle includes two reaction pathways. Reaction pathway 1 occurs under hydrophobic conditions and reaction pathway 2 occurs under hydrophilic conditions. ‘Gross work on actin molecule’ includes the energy necessary for the generation of M*_after and enthalpy production. Pathways 1 and 3 show a schematic illustration of energy balance in the cross-bridge cycle. Pathway 1 includes the generation process of M*_after from M*_before and the process of enthalpy production. The potential of the reaction product of two pathways at the goal is the same; therefore, the potential difference generated by pathway 2 covers gross work production on the actin molecule in addition to the energy required for the generation of M*_after (see text for details).