Data from: Hidden dynamics in the unfolding of individual bacteriorhodopsin proteins

Protein folding occurs as a set of transitions between structural states
within an energy landscape. An oversimplified view of the folding process
emerges when transiently populated states are undetected because of
limited instrumental resolution. Using force spectroscopy optimized for
1-microsecond resolution, we reexamined the unfolding of individual
bacteriorhodopsin molecules in native lipid bilayers. The experimental
data reveal the unfolding pathway in unprecedented detail. Numerous newly
detected intermediates—many separated by as few as two or three amino
acids—exhibited complex dynamics, including frequent refolding and state
occupancies of <10 μs. Equilibrium measurements between such states
enabled the folding free-energy landscape to be deduced. These results
sharpen the picture of the mechanical unfolding of membrane proteins and,
more broadly, enable experimental access to previously obscured protein
dynamics.