Official websites use .gov
A
.gov website belongs to an official
government organization in the United States.
Secure .gov websites use HTTPS
A lock (
) or https:// means you've safely
connected to the .gov website. Share sensitive
information only on official, secure websites.
Schematic illustration of helices. The side chains are in gray areas. The helices viewed along the main axes look not like circles (A) but have a flatter interface (B) created by shorter side chains (and by correspondingly longer side chains outside the interface). The effect brings them closer to each other and increases the helix–helix packing.
