Generating Ramachandran (phi/psi) plots for Proteins
On the parent page, I discussed how to load PDB files, calculate phi/psi angles (ϕ,ψ), and thus generate Ramachandran Plots (see references). Now you don't have to use python to do this...
If you want to double check the results from python (see calculating the angles), you could use the EMBOSS program psiphi, or Wolfgang Kabsch and Chris Sander's DSSP.
Instead of using python to draw the diagram, there are also a selection of online tools to draw Ramachandran Plots for you, including:
- Ramachandran Server for structures deposited in the PDB, based on MOLEMAN2 by Gerard Kleywegt.
- STAN Server which will accept any PDB file you provide, also based on MOLEMAN2.
- MolProbity from the Richardson laboratory at Duke University, which is used on the PDB website itself.
- RAMPAGE which will accept any PDB file you provide.
Using PDB 1HMP as an example, this is the sort of figure MOLEMAN2 produces (cropped for display):
MolProbity produces very nice images like this, extracted from this output :
This even more beautiful figure is from RAMPAGE, and shows the four plots combined. It was extracted from this output which also contains the data as four separate figures:
If you have the angles in a file, then you could draw the diagram yourself using R:
Finally, Peter Robinson's Java Program For Drawing Ramachandran Plots does a nice job of visualising the core/noncore regions as originally defined by Kleywegt and Jones (1996), or the Preferred/Allowed but Disfavoured/Forbidden regions introduced by Lovell et al (2003) (see references).