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. Author manuscript; available in PMC: 2013 Aug 1.
Published in final edited form as: J Am Chem Soc. 2012 Jul 19;134(30):12565–12577. doi: 10.1021/ja302528z

Figure 4.

Figure 4

Trp-Cys quenching studies of ACBP report slow unfolded-state intramolecular dynamics under folding conditions. (a) Observed quenching rates vs. time for loop W58-I86C in a fast mixer after diluting from 5 M to 0.2 M GuHCl, shown with an exponential fit to the data. (b) Linear dependence of W58-I86C quenching times (T=23C) with viscosity at ~1.4 ms, shown with a least-squares linear fit, R2 = 0.729. (T17C-W58 times are not shown as they are too slow to accurately measure.) (c and d) Reaction-limited kR (filled) and diffusion-limited kD+ (open) vs. [GuHCl] for (c) W58-I86C and (d) T17C-W58 loops. Red circles denote kR predictions from simulation data, and the dotted line reflects a lower limit of D at 0.2 M (see SI). (e) Intramolecular diffusion coefficients extracted from the W58-I86C data using SSS theory (see SI section B.4), and the red circle marks D calculated from simulated mean-squared displacements vs. time at 300K (0 M GuHCl).