Figure 3.

Sections of the nanotube models used for the NMR line shape simulations. The nanotube long axis Z (red arrow) is oriented perpendicular to the applied field B₀. a) Hydrogen-bonding (N–H) axis perpendicular to Z. b) Hydrogen-bonding axis parallel with Z. c) A generalized model, for which the N–H bond is oriented at angle θ relative to Z. The expanded regions (bottom) show the orientations of antiparallel β-strands (denoted by alternating red–blue arrows) in which the repeat distance along the hydrogen bonding axis is 4.7 Å and the distance between sheet layers is 10 Å. The models arbitrarily assume a parallel arrangement of the β-sheet layers.