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Psi and Phi Angles
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==Psi and Phi Angles of a Peptide Bond== | ==Psi and Phi Angles of a Peptide Bond== | ||
| - | + | <table width='500' align='right' cellpadding='5'><tr><td rowspan='2'> </td><td bgcolor='#eeeeee'><applet load='tetr_ala.mol' size='490' frame='true' align='right' scene ='Psi_and_Phi_Angles/First_view/1' caption='' /></td></tr><tr><td bgcolor='#eeeeee'><center>'''Peptide Segments Illustrating Secondary Structures'''<scene name='Psi_and_Phi_Angles/First_view/1'> (Initial scene)</scene></center></td></tr></table> | |
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<applet load='tetr_ala.mol' size='300' frame='true' align='right' scene ='User:Karl_Oberholser/Ramachandran_Plots/First_view/1' caption='Tetrapeptide' />Each peptide bond has two torsional angles - psi (ψ) and phi (φ) - which determine the geometry about the peptide bond. A tetrapeptide is used to describe and illustrate these two angles. | <applet load='tetr_ala.mol' size='300' frame='true' align='right' scene ='User:Karl_Oberholser/Ramachandran_Plots/First_view/1' caption='Tetrapeptide' />Each peptide bond has two torsional angles - psi (ψ) and phi (φ) - which determine the geometry about the peptide bond. A tetrapeptide is used to describe and illustrate these two angles. | ||
| - | <scene name=' | + | <scene name='Psi_and_Phi_Angles/First__view_planes/1'>Draw planes </scene> of two peptide bonds. The <scene name='Psi_and_Phi_Angles/First__view_psi/1'>four atoms </scene>making up ψ remain translucent, and the remaining atoms become transparent. After rotating the structure so that you can clearly see that you are not clicking on a transparent atom, determine and display the numerical value of ψ by double clicking on a nitrogen of the peptide bond, single clicking on the next two atoms and then double clicking on the second nitrogen. (If the structure rotates in the course of clicking on the atoms or if you encounter some other problem, re-click on the green link 'four atoms' and restart the clicking on the atoms.) The <scene name='Psi_and_Phi_Angles/First_view_phi/1'>four atoms</scene> making up φ remain translucent, and the remaining atoms become transparent. After rotating the structure so that the four atoms can be clearly seen, measure and display the numerical value of φ using the technique described above. <scene name='Psi_and_Phi_Angles/First_draw_rama/1'>Confirm</scene> the direction of rotation and the values of ψ and φ. |
== Determine values of other ψ and φ angles == | == Determine values of other ψ and φ angles == | ||
| - | <scene name=' | + | <scene name='Psi_and_Phi_Angles/First_view_planes2/1'>Draw the planes</scene> of two other peptide bonds, and then using the technique described above identify the atoms contained in and the numerical values of the ψ and φ angles of the α-carbon connected to these two planes. <scene name='Psi_and_Phi_Angles/Second_draw_rama/1'>Confirm</scene> that you obtain the correct values. |
[http://en.wikipedia.org/wiki/Torsional_angle Extensive description] of torsional angles. | [http://en.wikipedia.org/wiki/Torsional_angle Extensive description] of torsional angles. | ||
Revision as of 17:47, 6 October 2010
Psi and Phi Angles of a Peptide Bond
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of two peptide bonds. The making up ψ remain translucent, and the remaining atoms become transparent. After rotating the structure so that you can clearly see that you are not clicking on a transparent atom, determine and display the numerical value of ψ by double clicking on a nitrogen of the peptide bond, single clicking on the next two atoms and then double clicking on the second nitrogen. (If the structure rotates in the course of clicking on the atoms or if you encounter some other problem, re-click on the green link 'four atoms' and restart the clicking on the atoms.) The making up φ remain translucent, and the remaining atoms become transparent. After rotating the structure so that the four atoms can be clearly seen, measure and display the numerical value of φ using the technique described above. the direction of rotation and the values of ψ and φ.
Determine values of other ψ and φ angles
of two other peptide bonds, and then using the technique described above identify the atoms contained in and the numerical values of the ψ and φ angles of the α-carbon connected to these two planes. that you obtain the correct values.
Extensive description of torsional angles.
