  The helix is a ubiquitous motif for biopolymers. We propose a heuristic,
entropically based model that predicts helix formation in a system of hard
spheres and semiflexible tubes. We find that the entropy of the spheres is
maximized when short stretches of the tube form a helix with a geometry close
to that found in natural helices. Our model could be directly tested with
wormlike micelles as the tubes, and the effect could be used to self-assemble
supramolecular helices.
