Chemistry Reference
In-Depth Information
Figure 9.9 Probing conformational dynamics
within single, surface-immobilized molecules.
(A) Encapsulation of single molecules in lipid
vesicles. Immobilization of the trappedmolecule
is achieved indirectly by tethering the biotinylated
vesicle to a streptavidin-coated polymer coating.
As the diameter of the encapsulating vesicle
(
(B) Representative single-molecule folding
trajectories of encapsulated adenylate kinase
(AK) at denaturant concentrations around the
midpoint of unfolding, conditions at which the
native and denatured subpopulations are equally
populated. The top panel shows time traces of
the D- and A-emission (green and red,
respectively), employing 20-msec bin times.
D- and A-emission are anticorrelated, indicative
of conformational transitions within the
polypeptide. Notice however that the D-emission
continues to increase after bleaching of the
acceptor (t
100 nm) is considerably larger than the
diameter of the trapped molecule, the trapped
molecule can diffuse freely, thus minimizing a
perturbation of the energy landscape due to
confinement and non-productive interactions of
the trapped protein within the vesicle interior.
3 s), suggesting a variable
