HELIX: A helical diffraction simulation program

Abstract

The program HELIX has been devised as a simple aid to understanding the origin and appearance of fibre diffraction patterns from helical structures. Helices are common as preferred conformations in both natural and synthetic macromolecules (e.g. DNA, α-helices, polysaccharides, synthetic polymers), and occur frequently in extended macromolecular aggregates (e.g. actin filaments, myosin filaments, microtubules, amyloid filaments etc.). For this reason, a simple way of visualizing the kinds of diffraction patterns that these structures can give should have educational value and should also be useful as a quick means of testing possible symmetries in structural investigations before embarking on full helical diffraction analysis. Despite its simplicity, there is no other public program that provides these possibilities. The HELIX program, running under Microsoft Windows, is freely available from the CCP13 website (http://www.ccp13.ac.uk). © 2004 International Union Crystallography Printed in Great Bretain - all rigths reserved.