NMR analysis of ribbon and globular BuIA. The upper panels show the amide regions of the TOCSY spectra at 600 MHz of globular (A) and ribbon BuIA (B) at 282 K in 95% H2O/5% 2H2O at pH 3. The one letter code and the residue numbers are used for labeling. For globular BuIA (A) stretches of assigned residues are labeled, as a or b to indicate conformers A and B. The lower panels (C & D) show a secondary shift analysis of conformers A and B from globular BuIA and ribbon BuIA compared to AuIB. For each residue, represented by the one letter code, the differences between the actual chemical shifts for the α-protons and their respective random coil shifts are graphed. (C) Native AuIB (black bars), conformer A (white bars), conformer B (grey bars). (D) Ribbon AuIB (black bars), ribbon BuIA (white bars).