Figure 4
Analysis of the interaction of Ca2+4-CaM with TFP.
(a) Sequential binding model showing fitted dissociation and rate constants. (b) Observed and fitted 1H, 15N-HSQC spectra of 40 μM Ca2+4-CaM upon titration of TFP. Chemical shift changes are shown for K115, D118 and F141. D80 was excluded from the fitted region of interest and contours of the fitted I63, F68 and S101 resonances are desaturated to improve contrast for the remaining resonances. (c–f) Chemical shift differences (Δδ = (ΔδH2 + (ΔδN/5)2)1/2) between bound states, projected onto CaM-TFP crystal structures. Green spheres indicate calcium atoms. (c) 0–1 eq, pdb 1CTR27, 0–0.25 ppm yellow–red; (d) 1–2 eq, pdb 1A2929, 0–0.4 ppm yellow–red; (e) 2–3 eq, pdb 1LIN28, 0–0.7 ppm yellow–red; and (f) 3–4 eq, pdb 1LIN, 0–1 ppm yellow–red.
