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. Author manuscript; available in PMC: 2011 Feb 6.
Published in final edited form as: Curr Opin Struct Biol. 2010 Feb 6;20(1):63–69. doi: 10.1016/j.sbi.2010.01.003

Figure 4.

Figure 4

Lock-in SMFS. (a) In the length clamp mode, the sample is withdrawn at a constant velocity, while measuring the bending force of the cantilever. In this mode, each unfolding event is represented by a force peak. The figure shows a comparison between the results obtained with the lock-in mechanism (dark red and blue) [31] and the usual length clamp protocol, showing raw data (dark and light gray) as well as low-pass filtered (light red and blue) curves. This set up not only reduces noise of the curve, but also increases the sensitivity of the technique. (b) A hopping pattern is observed in the 4th Ig module of filamin by keeping a constant average length and amplifying the oscillation: the molecule jumps between the native, intermediate and unfolded states in apparent equilibrium. Figures obtained from ref. [31] with permission.