Figure 6.

Polarizer Rotation Measurements (PRM) to determine rotational position measurement error and to show F₁-ATPase-dependent 120° step rotations. (A) PRM measurement of a nonrotating AuNR attached directly to the cover slip. Red photons scattered from the AuNR were measured in 5 s intervals at a data sampling rate of 1 kHz (1,000 fps) at each 10° stepped rotational position of the polarizer. (B) PRM-dependent distribution of photons scattered from the non-rotating AuNR of A vs. rotary position of the polarizer. (C) Standard error of the AuNR rotary position vs. degrees of rotation from the minimum intensity calculated from B. This error is equivalent to that obtained from a data set of 3,250 power strokes. (D) PRM measurement of a AuNR attached to an actively rotating subunit-γ of the F₁-ATPase in the presence of saturating ATP concentrations. (E) PRM-dependent distribution of photons scattered from the non-rotating AuNR of A vs. rotary position of the polarizer. (F) PRM when the AuNR is attached to actively rotating F₁ subunit-γ, which stops rotating at polarizer angle 260°, likely due to subunit-ε inhibition. This figure was reconfigured from Spetzler et al. (2006), Ishmukhametov et al. (2010), Sielaff et al. (2016).