Difference between revisions of "Torsion angle"
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'''The angle between two bonds''' | '''The angle between two bonds''' | ||
− | + | [[Image:torsionangles.jpg|thumb|Overview of the different torsion angles]] | |
A torsion angle, also known as a dihedral angle, is formed by three consecutive bonds in a molecule and defined by the angle created between the two outer bonds. The [[backbone]] of a [[protein]] has three different torsion angles. | A torsion angle, also known as a dihedral angle, is formed by three consecutive bonds in a molecule and defined by the angle created between the two outer bonds. The [[backbone]] of a [[protein]] has three different torsion angles. | ||
*The [[phi-psi angle|phi-angle]] (φ) - around the N-Cα bond | *The [[phi-psi angle|phi-angle]] (φ) - around the N-Cα bond | ||
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The ω-bond has a slightly double bond character and is therefore almost always 180 degrees. The structure of a protein is mainly formed by the φ- and ψ-angles. <br> Every [[secondary structure]] element forces the [[backbone]] into a specific range of torsion angles, this can be visualized in a [[ramachandran plot]]. | The ω-bond has a slightly double bond character and is therefore almost always 180 degrees. The structure of a protein is mainly formed by the φ- and ψ-angles. <br> Every [[secondary structure]] element forces the [[backbone]] into a specific range of torsion angles, this can be visualized in a [[ramachandran plot]]. | ||
− | The | + | The figure shows the location of the φ, ψ and ω-angles<br> |
− | |||
[[Sidechain]]s can also contain torsion angles, they are indicated as [[chi-angle]]s. | [[Sidechain]]s can also contain torsion angles, they are indicated as [[chi-angle]]s. |
Revision as of 11:46, 3 August 2009
The angle between two bonds
A torsion angle, also known as a dihedral angle, is formed by three consecutive bonds in a molecule and defined by the angle created between the two outer bonds. The backbone of a protein has three different torsion angles.
- The phi-angle (φ) - around the N-Cα bond
- The psi-angle (ψ) - around the Cα-C bond
- The omega-angle (ω) - around the peptide bond between C and N.
The ω-bond has a slightly double bond character and is therefore almost always 180 degrees. The structure of a protein is mainly formed by the φ- and ψ-angles.
Every secondary structure element forces the backbone into a specific range of torsion angles, this can be visualized in a ramachandran plot.
The figure shows the location of the φ, ψ and ω-angles
Sidechains can also contain torsion angles, they are indicated as chi-angles.