Figure 4.

Derivation of the theoretical model. (A) Two hypothetical configurations of the system at (small) negative mismatch: (i) The helix is in vertical orientation, and the membrane thins to match the helix’s hydrophobic length. (ii) Driven by the precession entropy gain, the helix tilts by α from the normal, and the membrane thins further. (B) Two alternative configurations of the system for (small) positive mismatch in the range of 0–5 Å: (i) The helix is tilted by an angle γ from the membrane normal to match the native width of the hydrocarbon region of the membrane. (ii) Driven by the precession entropy contribution, the tilt angle increases to α (α > γ), and the membrane slightly thins. The helix is represented by a cylinder, with the hydrophobic core in purple and the polar termini in white. The membrane normal is marked by the vertical dashed line; the helix’s principal axis is marked by the solid line.