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Psi and Phi Angles
From Proteopedia
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| - | + | <table width='400' align='right' cellpadding='5'><tr><td rowspan='2'> </td><td bgcolor='#eeeeee'><applet load='tetr_ala.mol' size='390' 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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| - | + | We start with a tetrapeptide with a composition and sequence of LeuLeuIleTyr. As with any peptide the conformation of the backbone is determined by the values of two torsional angles - psi (ψ) and phi (φ) of each peptide bond. A tetrapeptide is used to describe and illustrate these two angles. | |
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== Determine values of other ψ and φ angles == | == Determine values of other ψ and φ angles == | ||
<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. | <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. | ||
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| + | == External Links == | ||
[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 18:35, 6 October 2010
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We start with a tetrapeptide with a composition and sequence of LeuLeuIleTyr. As with any peptide the conformation of the backbone is determined by the values of two torsional angles - psi (ψ) and phi (φ) of each peptide bond. A tetrapeptide is used to describe and illustrate these two angles.
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.
External Links
Extensive description of torsional angles.
