The unfolding kinetics of ubiquitin captured with single-molecule force-clamp techniques.

ABSTRACT: We use single-molecule force spectroscopy to study the kinetics of unfolding of the small protein ubiquitin. Upon a step increase in the stretching force, a ubiquitin polyprotein extends in discrete steps of 20.3 +/- 0.9 nm marking each unfolding event. An average of the time course of these unfolding events was well described by a single exponential, which is a necessary condition for a memoryless Markovian process. Similar ensemble averages done at different forces showed that the unfolding rate was exponentially dependent on the stretching force. Stretching a ubiquitin polyprotein with a force that increased at a constant rate (force-ramp) directly measured the distribution of unfolding forces. This distribution was accurately reproduced by the simple kinetics of an all-or-none unfoldin

SUBMITTER: Schlierf M 

PROVIDER: S-EPMC409913 | biostudies-literature | 2004 May

REPOSITORIES: biostudies-literature