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.
Four most designable distinct four-helix folds: (a) up-and-down fold, (b) up-and-down with a crossover connection fold, (c) λ-repressor-type fold, (d) orthogonal-array fold. Numbers indicate helix number and their location indicates the beginning of the given helix.
