Ability of the hydrophobic core of α2D variants to adopt a unique conformation as assessed by 1D 1H-NMR spectroscopy at 500.13 MHz. Proton spectra at 2 mM monomer concentration in 50 mM d11-Tris, pH 7.3 for (a) α2D, E7A, E7S, E7D and E7H, and (b) α2D, E7Y, E7F, E7V and E7L at the temperature of maximum thermal stability. The methyl region of each spectrum is shown and is essentially a fingerprint of the hydrophobic core for each protein.