Plot of the backbone amide chemical-shift changes (Δδ) against residue numbers in Spα1-156Arg45Ser and Arg45Thr relative to Arg28/Arg45, and missing resonances in Arg45Ser.

Sample identity is indicated at the top of each plot. Normalized chemical-shift changes in the top 2 plots were calculated as described in “Materials and methods.” Residues that could not be identified because of changes in the mutant spectra (residues 44, 45 in Arg45Thr; and 42, 45 in Arg45Ser) are left blank. The bottom plot notes resonances missing in the Arg28Ser HSQC spectrum, as compared with that of the native peptide.