Substeps in F1 Rotation

Solid
horizontal lines are drawn 120° apart, and dotted lines are
30° below. |
|
|

Slow
playback at 1/1067 the original speed (recorded at 8,000 frames per
second)
|
|
|
At
speeds below the maximal, we were able to resolve substeps with an
amplitude of ~90 °
and ~30°
in the 120° step powered by the hydrolysis of one ATP molecule (see
figure at left). If you have very good eyes, you may be able
to detect some of the substeps in the actual images on the
right. The 90° substep turned out to be driven by
binding of ATP to a catalytic site on F1,
and the 30° substep by the release of a hydrolysis
product(s). The hydrolysis reaction per se appeared to be
mechanically almost silent.
|