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3-Dimensional Structure of Proteins. 4 levels of protein structure:. Alpha Helix Common structure: ~25% of all amino acid residues! (hair…) Optimal use of internal hydrogen bonding: 1st -4th. Alpha-helices are generally right handed. 3. 7. 4. 6. 2. 1. 5.
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Alpha Helix Common structure: ~25% of all amino acid residues! (hair…) Optimal use of internal hydrogen bonding: 1st -4th Alpha-helices are generally right handed
3 7 4 6 2 1 5
Alpha helices have an intrinsic dipole: Interactions of R groups with dipole: Stabilizes or destabilizes the alpha helix 3 constraints affect stability of alpha helix: 1)interactions between adjacent R groups • steric • electrostatic 2) Occurrence of Pro and Gly 3) interactions between AAs at end of helix and intrinsic dipole
Characteristics of alpha helices: Not limited to coiled-coils!! Common structural units
Proteins can have mostly alpha helix, beta sheet, or both Other secondary structures also exist! (tomorrow…)