Energy Calculation in Rosetta3.4

Depending on how you define “free energy” and “total energy”, this is easy. Rosetta does not calculate in physical energy units (kcal/mol), it calculates in Rosetta Energy Units, which don’t directly convert to physical energies. Read some of Kellog and Baker’s papers on DDGs to learn how they’ve tried to get a scorefunction that reports in kcal/mol.

Anyway, if you’ll take Rosetta’s scores as answers, then make a file containing the filenames of all your pdbs (like, say “ls *pdb > pdblist”), and pass it to the score_jd2 app with the -l flag:

score_jd2.release -database /path/to/database -l pdblist -jd2:delete_old_poses

For 100,000, scoring is fast, but you may want to use MPI if it’s available. (You need delete_old_poses to prevent a memory leak that occurs in this situation)

The first column, marked “score”, is the weighted sum of the other terms, and is used as the overall energy.

Those are scores that indicate Rosetta hates the structures, BTW – you should have something like -2 per residue, you have something positive. The positivity is in your fullatom repulsive (fa_rep) term.

No…if there are 100 residues total, you should expect fullatom scores between -100 to -300, depending on the quality of the structure. A positive score means Rosetta things the structure has a positive folding energy – in other words it won’t fold that way. (Usually this is due to a clash).

Keep in mind that “clashes” are *very* common in structures which come directly from the PDB. Rosetta’s energy function is sensitive enough that small coordinate changes which aren’t necessarily experimentally relevant can have a great effect on the reported energy. (And even a small clash in some distal part of the protein can greatly affect the score.)

It’s commonly suggested that from-PDB structures should be relaxed into the Rosetta energy function before relying on the score. The recently-released Rosetta 3.4 now has a simple protocol to do a heavy-atom constrained relax, which in our experience can greatly improve the energy without significantly changing the atom positions (i.e. all-atom RMSDs in the tenths of angstoms). ( See http://www.rosettacommons.org/manuals/archive/rosetta3.4_user_guide/d9/d2e/prepare_pdb_for_rosetta_with_relax.html, sections labeled with “Relax with all-heavy-atom constraints”)