Chemistry Reference
In-Depth Information
Figure 2.3 Simultaneous observation of individual ATP hydrolysis
and mechanical events by single myosin molecules. (a) A
schematic drawing of the experimental setup [15]. (b) Time traces
of displacements (upper trace) and changes in the fluorescence
intensity from Cy3
-
nucleotides (ATP or ADP) bound to myosin
(lower trace).
problem, we developed a more direct method to capture a single myosin molecule
andmeasure its displacements by using a scanning probe. The series stiffness during
acto
-
S1 interaction signi
cantly increased to
1 pN/nm, compared to that obtained
with optical trapping experiments (0.05
-
0.2 pN/nm). The resulting thermal
uctua-
tions of the probe, namely the noise of the measurements, were reduced from
4
-
9nm
rms
to
>
2nm
rms
. This improvement was critical to the resolution of the
process generating the
<
10
-
20-nm displacements. Furthermore, a myosin head
rigidly attached to a relatively large scanning probe could steadily interact with actin
without diffusing away from the actin
filament, as it does in muscle to slow its
motion.
