Fluctuation Theorem Applied to F1-ATPase

In recent years, theories of nonequilibrium statistical mechanics such as the fluctuation theorem (FT) and the Jarzynski equality have been experimentally applied to micro and nanosized systems. However, so far, these theories are seldom applied to autonomous systems such as motor proteins. In particular, representing the property of entropy production in a small system driven out of equilibrium, FT seems suitable to be applied to them. Hence, for the first time, we employed FT in the single molecule experiments of the motor protein F-1-adenosine triphosphatase (F-1), in which the rotor gamma subunit rotates in the stator alpha(3)beta(3) ring upon adenosine triphosphate hydrolysis. We found that FT provided the better estimation of the rotary torque of F-1 than the conventional method.