SB228 Lecture 3 Lecture3 Lecture 3 Contents Helix-Helix Packing. Concept 3.1 Helix-Helix-Packing Pairs of Alpha-Helices Helix Ridge Lines Common Helix Packings Helix Packing Omega 140 -40 Helix Packing Omega 20 -160 Common Helix Packings Revisited