Fig. 3

Residues 201–250 adopt three partial populated α-helices. A (Top) Schematic representation as gray cylinders of the three partially populated helices present in residues 200–250. (Bottom) One conformer with all three α-helices is shown; residues are colored: cationic residues (R and K) = blue, aromatics (F, Y, W and H) = purple, anionic (E and D) = red, aliphatic (A, I, L, M) = dark gray, amyloidogenic (N and Q) = magenta, hydroxyl bearing (S and T) = cyan, and proline = green. B ¹³CO (black) and ¹³Cα (blue) conformational chemical shifts (Δδ) of residues 201–250 at 25 °C. Note that the second α-helix which contains nine consecutive Ala residues has a relatively high helical population. Uncertainties in the conformational chemical shifts (Δδ) are 0.02 and 0.10 ppm for ¹³CO and ¹³Cα, respectively. C {¹H}-¹⁵ N NOE ratios. Values shown in dark blue are of individual ¹H¹⁵N resonances; those in light blue correspond to overlapped peaks. D R_1ρ values reveal the ps/ns and µs/ms time scales. Significantly higher {¹H}-¹⁵ N NOE ratios and R_1ρ values are observed for these residues at 5 °C (Additional File 1. Fig. S10)