User talk:Norbert Sträter
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Welcome to Proteopedia! We hope you will contribute much and well. You will probably want to watch the narrated video guide and use the help pages for later reference. Again, welcome and have fun! . Eric Martz 15:40, 13 January 2023 (UTC)
Phi and Psi dihedral angles
Hello Norbert.
I think your amendment in the Ramachandran Plot page is not correct and should be reverted.
This is a peptide backbone around the alpha carbon in residue "i":
C(i-1) = N(i) |phi| CA(i) |psi| C(i) = N(i+1)
where "=" represents the peptide bond and "|" the bonds whose rotation corresponds to phi and psi rotations
Therefore, phi angle is defined by the first 4 atoms, with phi=0 when both carbonyl carbons are aligned (eclipsed)
while psi is defined by the last 4 atoms,and has zero value when the two nitrogens are eclipsed
Please check other pages dealing with this, e.g.
Best, --Angel_Herraez 09:02, 1 February 2023 (UTC)
Hello Angel,
thanks for noticing that. Actually the original version and my correction (reverted) were both wrong. I noticed that in the original version, Phi defined an angle rotating around the Ca-C bond and Psi an angle rotating around the N-Ca bond. So I reverted the definitions. But I did not check that the angles should be defined for amino acid i. I think now it is correct.
Best, Norbert
