Figure 4.

Measurement of CaM-CaMKI peptide association rates and determination of k_on. (A) A representative association experiment for CaMKI peptide is shown to illustrate data collection and fitting. CaM association rates were measured under pseudo first-order binding conditions and the data shown represent averages spanning a range of peptide concentrations (black to red scatter plots), with only every 20th data point plotted for clarity. Data was fit with single-exponential rates to determine observed rates, k_obs. Observed rates for each concentration were then plotted as a function of CaMKI peptide concentration (inset) and the k_on value was determined from the slope of the linear fit. This experimental procedure was repeated in varying concentrations of ficoll-70 (B), dextran-10 (C), and sucrose (D) to determine rates. Experiments were completed in duplicate. Error bars represent mean ± SE. To see this figure in color, go online.