3-Dimensional Structure of Proteins

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3-Dimensional Structure of Proteins
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4 levels of protein structure
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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
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3
7
4
6
2
1
5
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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
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Characteristics of alpha helices
Not limited to coiled-coils!! Common structural
units
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Proteins can have mostly alpha helix, beta
sheet, or both
Other secondary structures also exist!
(tomorrow)