Figure 3.

Titrations of WT and mutant ¹⁵N,¹³C-labeled C₂AB fragments with SNARE complex monitored by 1D ¹³C-edited ¹H-NMR spectra. A. Plot of the SMR intensities observed in 1D ¹³C-edited ¹H-NMR spectra of 3 µM WT C₂AB fragment as a function of unlabeled SNARE complex concentration in the presence of 1 mM Ca²⁺. B-D. Plots for analogous titrations performed with DN (B), RR (C) and KK (D) mutant C₂AB fragments (open squares), superimposed with a plot obtained for the WT C₂AB fragment (closed circles; the same shown in A). The curves show the fits of the data obtained with equation (1).