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.
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The secondary protein structure a polypeptide is the small part and polypeptide sequence, curls up into an alpha helix or beta pleated sheets.
Plots generated in this study clearly indicate that there are geometric shifts in the polypeptides as a function of the form in which they are minimized, and compares polyalanines with 50 residues for a sheeted structure (five parallel sheets), an alpha helix and a beta helix, with the alpha structure showing the widest range of angles.
Together, Watson and Crick aspired to solve the structure of DNA by model building, just as Pauling had done for the alpha helix in proteins.
My new awakening led me to Alaska again for a solo springtime trek, 75 miles over the Resurrection Pass from a town called Hope on the Turnagain Arm of the Cook Inlet (near Anchorage) to Seward, the home port of the R/V Alpha Helix, near Prince William Sound.
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 grubby sculpin protein has a tight spiral structure known as an alpha helix.