Figure 10.

Location of residues exhibiting significant correlated conformational exchange contributions to CSM/CSM CCR rates in the E140Q mutant of the C-terminal domain of calmodulin. A) Residue pairs exhibiting dynamics sensed by CSM(¹⁵N)/CSM(¹H^N) CCR rates in apo wild type are highlighted from yellow to red, for increasing contributions. Residues for which MQ rates could not be measured are shown in gray. B) Same as A) for calcium-loaded wild type. C) Residue pairs exhibiting dynamics sensed by CSM(C^α_i)/CSM(C^α_i+1) CCR rates in calcium-loaded E140Q mutant are highlighted in red or blue, depending on whether the CSM/CSM of the two residues are correlated or anticorrelated. Residues for which MQ rates could not be measured or without significant dynamics are shown in white and gray, respectively. D) δσ_Nδσ_HN values for the of the E140Q mutant extracted from CSM(¹⁵N)/CSM(¹H^N) CCR rates plotted in A) and B) (black dots). The magenta line shows δσ_Nδσ_HN calculated from the chemical shifts of the apo and calcium-loaded wild type (δσ = Δω/γ/Β_ο.). The blue line shows values calculated from δσ_HN ring-current contributions and δσ_N measurements on the mutant. E) Measured differences between DQ- and ZQ-coherence relaxation rates, which are dominated by CSM(C^α_i)/CSM(C^α_i+1) CCR and used for C). For comparison, exchange rates of H^N with the solvent are shown (solid continuous line). F) Secondary ¹³C^α chemical shifts for calcium-loaded E140Q mutant are shown in white bars, and chemical shift differences between apo and calcium-loaded wild type in black bars. C), E) and F) P. Lundström, F.A.A. Mulder, M. Akke, Correlated dynamics of consecutive residues reveal transient and cooperative unfolding of secondary structure in proteins. Proc. Natl. Acad. Sci. USA, 2005, 102, 16984–16989, copyright 2005 National Academy of Sciences. A), B) and D) Reprinted with permission from P. Lundström, M. Akke, Quantitative analysis of conformational exchange contributions to ¹H-¹⁵N multiple-quantum relaxation using field-dependent measurements. Time scale and structural characterization of exchange in a calmodulin C-terminal domain mutant. J. Am. Chem. Soc., 2004, 126, 928–935, copyright 2004 American Chemical Society.