Fluctuation Analysis of Mechanochemical Coupling Depending on the Type of Biomolecular Motors

摘要

Mechanochemical coupling was studied for myosin Ⅱ and Ⅴ consistently. The fluctuation in myosin Ⅴ motility was determined by correlating the stochasticity of the ATPase reaction with regular displacements per one ATP, consistent with a tight mechanochemical coupling. In contrast, myosin Ⅱ, working in an ensemble, was explained by a loose coupling, generating variable step sizes which depend on [ATP] and realizing a much larger step (200 nm) per one ATP than myosin Ⅴ through its cooperativity at zero load. These different mechanics are ideal for their physiological functions.