Figure 4.

Sequences and structure models of helical peptides WWALP23 (a) and GWALP23 (b). The helices are viewed from the N-terminus along their long axis, such that the tilt vector (T) is pointing to the right and has a length proportional to the experimental τ angle (values corresponding to DLPC membranes, determined in (6) using ²H NMR splittings from (17)). The azimuthal rotation ρ, also from experiments (6,17), is defined relative to the radial position of the C^α of residue G¹. The side chains of the flanking tryptophans (W², W²², W⁵, and W¹⁹) and relevant hydrophobic residues (L⁴, L²⁰) are represented by sticks, in arbitrary conformation. Underneath are shown the hydrophobic and flanking Δ-heights for relevant residues (labeled in the graphs) of WWALP23 (c) and GWALP23 (d) as functions of ρ for their respective experimental τ. The experimental values of ρ are marked in the plots with vertical bars. The horizontal dotted line corresponds to the estimated hydrophobic thickness of liquid crystalline DLPC (20.9 Å (28)).