Comment on "Force-Clamp Spectroscopy Monitors the Folding Trajectory of a Single Protein"

In a recent experiment ([ 1 ][1]), the folding of a single polyprotein consisting of nine N-C linked ubiquitin repeats was monitored under a constant force with an atomic force microscope (AFM). Unlike the discrete, staircase-like increase in the length of the polyubiquitin chain observed in