Monte Carlo study for fluctuation analysis of the in vitro motility driven by protein motors

The fluctuation properties of the sliding movement of an individual cytoskeletal filament driven by protein motors in vitro can be analyzed by calculating the mean-square deviation of the displacement from the average within its single trajectory. For this purpose, a Monte Carlo simulation was used to define the conditions and limitations of a method for smoothing (curved) noisy trajectories without affecting either the steady or fluctuation characteristics inherent to the individual filament sliding movement. By applying the method to real experimental trajectory data, we show that an effective diffusion coefficient from displacement fluctuations of a sliding filament can be obtained from its single noisy trajectory even when it is curved.