MBIO 2360 Lecture Notes - Lecture 7: Hydrophile, Egg White, Hemoglobin
1 Dec 2016
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Document Summary
The polypeptide backbone or main chain has regularly spaced hydrogen-bonding elements, c=o and n-h. If these two elements come together in space, a h-bon can form: Not the side chains that causes this - its just the backbone. Secondary structure describes how parts of the sequence fold in a regular way so as to maximize the number of h-bonds. There are two main types of secondary structure: Initially defined by linus pauling - essentially an extended right handed spiral or spring. One turn of helix - 5. 4 angstrom - 3. 6 residues. Stabilized by the h on the n and c=o of another. The c=o are all pointing in one way - towards the c terminus in a right spiral. The charged amino acids are on one side and the hydrophobic ones are on the other side. The peptide bond has a planar or double bond character. The c-n bond is shorter and rotation is constrained.
