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| - | ====Repetitive torsion angles ====
| + | <br><br> |
| - | <applet load='180-180.pdb' size='400' frame='true' align='right' scene='User:Tilman_Schirmer/Sandbox_100/Extended/2'/>
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| - | | + | |
| - | A polypeptide chain with a repetition of identical phi-psi torsion angles yields a helical structure.
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| - | | + | |
| - | ----
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| - | phi-psi = (180<sup>o</sup>, 180<sup>o</sup>), fully extended chain:
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| - | <scene name='User:Tilman_Schirmer/Sandbox_100/Extended/2'>model</scene>,
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| - | <scene name='User:Tilman_Schirmer/Sandbox_100/Extended/3'> Calpha-trace</scene><br>
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| - | | + | |
| - | ----
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| - | phi-psi = (-140<sup>o</sup>, 130<sup>o</sup>), extended chain:
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| - | <scene name='User:Tilman_Schirmer/Sandbox_100/Beta/1'>model</scene>,
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| - | <scene name='User:Tilman_Schirmer/Sandbox_100/Beta/2'>Calpha-trace</scene>; this is the '''β-strand''' conformation found in beta-sheets <br>
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| - | Note: <br>
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| - | polypeptide forms a <scene name='User:Tilman_Schirmer/Sandbox_100/Beta/4'>zig-zag</scene> with side-chains protruding towards alternating (up, down) directions<br>
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| - | the polypeptide main-chain is <scene name='User:Tilman_Schirmer/Sandbox_100/Beta/3'>right-twisted</scene> as can been seen when looking along the chain <br>
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| - | the <scene name='User:Tilman_Schirmer/Sandbox_100/Beta/5'>side-chains</scene> point towards alternate directions<br>
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| - | ----
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| - | phi-psi = (70<sup>o</sup>, 180<sup>o</sup>):
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| - | <scene name='User:Tilman_Schirmer/Sandbox_100/Elongated_helix/1'>model</scene>,
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| - | <scene name='User:Tilman_Schirmer/Sandbox_100/Elongated_helix/2'>Calpha-trace</scene>; note that there are clashes (where?)<br>
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| - | | + | |
| - | ----
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| - | phi-psi = (-60<sup>o</sup>, -40<sup>o</sup>), '''α-helix''':
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| - | <scene name='User:Tilman_Schirmer/Sandbox_100/Helix/1'>model</scene>,
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| - | <scene name='User:Tilman_Schirmer/Sandbox_100/Helix/2'>Calpha-trace</scene><br>
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| - | | + | |
| - | ----
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| - | phi-psi = (-50<sup>o</sup>, -26<sup>o</sup>), '''3<sub>10</sub> helix''':
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| - | <scene name='User:Tilman_Schirmer/Sandbox_100/310helix/1'>model</scene>,
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| - | <scene name='User:Tilman_Schirmer/Sandbox_100/310helix/2'>Calpha-trace</scene>
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| - | ----
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| - | ==== α-Helix ====
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| - | <applet load='180-180.pdb' size='400' frame='true' align='right' scene='User:Tilman_Schirmer/Sandbox_100/Helix/1'/>
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| - | An α-Helix is stabilized by main-chain <scene name='User:Tilman_Schirmer/Sandbox_100/Helix/3'>hydogen bonds</scene> between O<sub>i</sub> and N<sub>i+4</sub>. With <scene name='User:Tilman_Schirmer/Sandbox_100/Helix/4'>side-chains</scene>.
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| - | | + | |
| - | | + | |
| - | <br><br><br><br><br><br><br><br><br><br><br><br><br><br><br><br><br><br><br><br><br>
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| - | | + | |
| - | ==== parallel β-sheet ====
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| - | <applet load='1tmy.pdb' size='400' frame='true' align='right' scene='User:Tilman_Schirmer/Sandbox_100/Parallel_sheet/4'/>
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| - | With <scene name='User:Tilman_Schirmer/Sandbox_100/Parallel_sheet/5'>side-chains</scene>.
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| - | | + | |
| - | | + | |
| - | <br><br><br><br><br><br><br><br><br><br><br><br><br><br><br><br><br><br><br><br><br><br><br>
| + | |
| - | | + | |
| - | ==== antiparallel β-sheet ====
| + | |
| - | <applet load='1ema.pdb' size='400' frame='true' align='right' scene='User:Tilman_Schirmer/Sandbox_100/Antiparallel_beta-sheet/1'/>
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| - | With <scene name='User:Tilman_Schirmer/Sandbox_100/Antiparallel_beta-sheet/2'>side-chains</scene>.
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| - | | + | |
| - | | + | |
| - | <br><br><br><br><br><br><br><br><br><br><br><br><br><br><br><br><br><br><br><br>
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| | | | |
| | == Anatomy of a protein == | | == Anatomy of a protein == |
