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. Author manuscript; available in PMC: 2013 Dec 18.
Published in final edited form as: Biochemistry. 2012 Dec 4;51(50):10075–10086. doi: 10.1021/bi3009104

Figure 5.

Figure 5

Stopped-flow fluorescence traces of K48-linked IQF diubiquitin binding to the USP2 catalytic core. (A) Fluorescence enhancement associated with the TAMRA fluorophore in the IQF diubiquitin substrate was monitored over 10 seconds to follow the binding of K48-linked IQF diubiquitin to USP2. USP2 concentration was varied (1, 2, 3, 5, 7, and 9 μM) while K48-linked IQF diubiquitin concentration was held constant at 0.4 μM. The data set was fit to a single or double exponential function for a comparison. The double exponential fitting results are shown as black lines. Residuals for the single (B) and double (C) exponential fitting to a representative binding trace for 9 μM USP2 and 0.4 μM K48-linked IQF diubiquitin are shown. Analyses of the residuals reveal that a double exponential function provides a significantly better fit to the data.