This design puzzle ended 26 January 2011.
This is one of the first puzzle pages on the Foldit wiki, and it relied on the images posted on the Foldit server. Unfortunately, the Foldit team decided to prune older images to resolve a disk space problem, so the following links now give "404 - not found" errors:
There's always a chance some kind person will restore the deleted images from a backup, so we'll continue to hold out hope.
The first three images were submitted by anthunk, the fourth by Mark-.
Anthunk said "amino sequence is His-Arg-Lys-Arg-Glu-Ala-Ala for the mutable part".