BCH 2333 Lecture 7: 3D structure of proteins - secondary and tertiary
4 Mar 2016
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Document Summary
Tertiary structure - section 6. 6, quaternary struc - 6. 7. A helix characterized by the number, n, of peptide units per helical turn and by its pitch, p, the distance the helix rises along its axis per turn. Negative n = left handed, positive n = right handed helix o o. Right handed alpha helix o o o n=3. 6 residues per turn p=6. 4 angstroms per turn. Dotted lines connecting the strands of the helix. Nh of the nth residue h bonds to the co of the nth +4 residue. Length: 12 - 14 amino acids (typically there are 20 amino acids) Tight packing in core - very little empty space. Water can"t access the inside or outside of the helix because of the r groups and the tight packing. Space filling representation of an alpha helical segment of sperm whale myoglobin o. The hydrogen bonding pattern of several polypeptide helices.
