alpha helix

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alpha helix

[′al·fə ′hē·liks]
(cell and molecular biology)
A spatial configuration of the polypeptide chains of proteins in which the chain assumes a helical form, 0.54 nanometer in pitch, 3.6 amino acids per turn, presenting the appearance of a hollow cylinder with radiating side groups.
McGraw-Hill Dictionary of Scientific & Technical Terms, 6E, Copyright © 2003 by The McGraw-Hill Companies, Inc.
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A helix is characterized by both its radius r and pitch h.
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As an alternative, a new screw was designed, retaining the existing channel depths, section lengths and compression ratio, but with a slightly shorter flight lead to give a helix angle that simulations said would increase the feed rate.
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There, parallel strands that would normally lie in a flat sheet instead curl into a helix. Each turn of a beta helix consists of three beta segments, with 22 amino acids per turn, so the structure is about five times as wide as an alpha helix.
The first product, already under development, will work with ResearchStation, a Helix Systems software product that provides scientists and scientific organizations with dramatic improvements in their ability to access, integrate, and share information at the desktop.